Image processing device and method

ABSTRACT

In order to achieve to adjust saturation of an image without leading to a deterioration in image quality, there is provided an image processing device and method in which a conversion data has a conversion characteristic which suppresses a change in saturation in a visible image for pixels belonging to a predetermined color region, and in order to achieve that changes in image quality which accompany conversion of gradation of an image data can be accurately corrected, there is provided an image processing device and method in which one of reconverting the image data which is converted or controlling a conversion characteristic is performed, such that changes in a ratio of a difference, of each of color components, with respect to gray of each pixel of the image data, which changes accompany conversion of the gradation of the image data, are corrected.

BACKGROUND OF THE INVENTION

This application is a Divisional of co-pending Application No.09/906,669, filed on Jul. 18, 2001, the entire contents of which arehereby incorporated by reference and for which priority is claimed under35 U.S.C. § 120.

1. Field of the Invention

The present invention relates to an image processing device and method,and in particular, to an image processing device which converts imagedata such that saturation of an image is changed, and to an imageprocessing method which can be applied to the image processing device.Further, the present invention relates to an image processing methodwhich can convert the gradation of image data, and to an imageprocessing device to which the image processing method can be applied.

2. Description of the Related Art

In research and development of photosensitive materials such asphotographic films, photographic printing papers and the like, it isknown that, in order to realize vivid color formation of a photographedimage, when a photosensitive material is exposed by using amonochromatic light whose main light is a specific color component(RGB), the developing suppressing effect from other color photosensitivelayers weakens (the so-called interlayer effect) as compared to a casein which exposure is carried out by using white light. As a result, thephotosensitive layers must be designed such that the saturation of theregions corresponding to chromatic photographed subjects is reproducedeven higher than the saturation in regions corresponding to photographedsubjects in the photographed image which are achromatic or nearlyachromatic.

In images of landscapes or objects at rest, by increasing the saturationof chromatic photographed subjects throughout the entire image asdescribed above, the image has an apparently vivid finish. However, forimages which include humans as photographed subjects, when thesaturation of skin-colored regions corresponding to the skin of personsin the image is increased more than needed due to the increase in thesaturation of the entire image, a problem arises in that thephotographed image does not have a preferable finish, for example, theredness of or pimples on a person's face or the like are emphasized morethan needed. Thus, for image quality, there is a tradeoff between thesaturation of the entire image and the saturation of the skin-coloredregions.

On the other hand, in image processing carried out on digital imagedata, it is possible to relatively easily and freely adjust and changethe color reproduction of the image. For example, in 3×3 matrixprocessing in which a 3×3 matrix is multiplied by each pixel for RGB3-channel image data, if the diagonal elements of the 3×3 matrix aremade to be values larger than 1 and the non-diagonal elements are madeto be values smaller than zero, the saturation can be increased. If thediagonal elements of the 3×3 matrix are made to be values less than 1and the non-diagonal elements are made to be values greater than zero,the saturation can be decreased. However, in this case as well, when thesaturation of the entire image is increased, the skin-colored regionscorresponding to the flesh of people in the image have a finish which isnot preferable.

Further, Japanese Patent Application Laid-Open (JP-A) No. 6-124329discloses a saturation changing circuit used in a structure in which, onthe basis of an inputted color signal, a multiplication factorexpressing the degree of enhancement of the saturation is determined bya saturation detecting circuit, and due to a saturation raising circuitmultiplying the determined multiplication factor by the saturationsignal, the saturation is raised. In the saturation changing circuit, afactor for skin-color judgement is set by the saturation detectingcircuit. At a specific-color judging circuit, on the basis of the hue ofthe inputted signal and the factor set by the saturation detectingcircuit, a judgement is made as to whether that hue falls within a rangeof skin color. In a case in which it is judged that the hue falls withinthe range of skin color, the multiplication by the saturation raisingcircuit (i.e., the raising of the saturation) is stopped.

However, in the aforementioned saturation changing circuit, thesaturation is changed by turning the saturation raising by thesaturation raising circuit on and off on the basis of whether the hue ofthe inputted signal falls within a range of skin color. Thus, when thesaturation is changed by the saturation changing circuit, a problemarises in that the image quality deteriorates, such as the finish in thevicinity of the outer edges of regions at which the saturation is raisedby the saturation raising circuit and regions at which the saturation isnot raised is unnatural. Further, in the saturation changing circuit,when an attempt is made to suppress the raising of the saturation of aplurality of respectively different hues, it is necessary to provide aspecific-color judging circuit for each of the hues for which raising ofthe saturation is to be suppressed, and a problem arises in that thestructure of the device becomes complex.

Further, the color reproduction characteristics which are preferable atthe time of reproducing an object, which is photographed by a camera, asan image on a recording medium differ in accordance with the type of thephotographed object, the uses of the image, and the like. Thus, pluraltypes of photographic photosensitive materials having respectivelydifferent characteristics are developed and produced as photographicphotosensitive materials such as photographic films, photographicprinting papers, and the like. For example, in a case in whichphotographing is carried out by a professional cameraman (especiallyphotography at a photo studio or photography for portraiture) andphotographic prints are prepared from the images recorded on thephotographic film by this photographing, a photographic film orphotographic printing paper is used which has a soft gradation (lowcontrast) characteristic by which it is difficult for over color andunder color (color loss in gradation separation) to arise in the regioncorresponding to the face of a person in the image. On the other hand,for general photography or amateurs, vivid color prints are preferable,and therefore, photographic films or photographic printing papers havinghard gradation (high contrast)characteristics are usually used.

Further, different types of photographic photosensitive materials areused for different types of photographed subjects, differentapplications of the images, and the like. For example, a photographermay select the photographic film and carry out photographing inaccordance with his/her personal tastes or the type of the object to bephotographed or the like. At the place of development to which thephotographic film is brought and at which preparation of photographicprints is requested, for example, if the person placing the request is aprofessional cameraman, the preparation of the photographic prints maybe carried out by using a photographic printing paper which has beendeveloped for professional use (e.g., a photographic printing paperhaving a soft gradation characteristic).

However, in order realize such use of different types of photographicphotosensitive materials for different types of photographed subjects ordifferent applications of images or the like, it is necessary to preparein advance plural types of photographic photosensitive materials havingrespectively different characteristics. Thus, the financial burden isheavy, and the work involved in properly using the different types ofphotographic photosensitive materials in accordance with the differenttypes of photographed subjects, different applications of the images andthe like is complex.

Thus, the image data, which is acquired by reading by photoelectricconverting elements an image recorded on a photographic film, isconverted in accordance with a gradation conversion characteristic whichis determined in accordance with the type of the photographed subject,the application of the image, or the like. The image data which has beensubjected to gradation conversion is used to record the image onto aphotographic photosensitive material. In this way, photographic printsof a finish which corresponds to the type of the photographic object orthe application of the image or the like can be prepared from one typeor a few types of photographic photosensitive materials. However, whenthe gradation of the image data is converted, a problem arises in thatan unintentional change in the image quality (especially a change in thesaturation) arises.

As a related technique, JP-A No. 5-328132 discloses a digital imageforming device such as a digital printer or a digital copier. When theuser inputs a target gradation curve by an inputting section, an emittedlight controlling section corrects the exposure data on the basis of theinputted gradation curve. Due to a color masking correcting sectioncarrying out color masking correction in accordance with the input ofthe gradation curve, adjustment is carried out such that the (saturationand the like) of the output image does not change even if the gradationcurve changes.

However, in the technique disclosed in the aforementioned publication,by carrying out matrix computation, color masking correction isrealized, and the control of the hardness/softness of the gradation andthe control of the increase/decrease in saturation can be made tocorrespond to each other. For example, when a gradation curve in whichthe saturation becomes high is selected, a masking factor whichdecreases the saturation is selected as the masking factor (matrixfactor) used in color masking correction, and a change in the saturationcan thereby be suppressed. The adjustment of the saturation changeamount is carried out by adjusting the values of the non-diagonalelements of the masking factor.

Thus, in cases such as when a gradation curve whose slope (and inparticular, slope from the highlight regions to the shadow regions) isnot constant is selected, it is difficult to accurately correct thechange in the image quality such as saturation or the like from thehighlight regions to the shadow regions. A problem arises in that theaccuracy of correction with respect to changes in image quality thataccompany image gradation conversion is poor.

SUMMARY OF THE INVENTION

In view of the aforementioned, a first object of the present inventionis to provide an image processing device and method in which it ispossible to adjust the saturation of an image without leading to adeterioration in image quality.

Further, a second object of the present invention is to provide an imageprocessing device and method in which changes in image quality whichaccompany conversion of gradation can be accurately corrected.

In order to achieve the above object, an image processing devicerelating to a first aspect of the present invention includes a storingsection which stores conversion data of a conversion characteristicwhich changes, in units of respective pixels and by a predeterminedamount, saturation, in a visible image, of image data used in output ofthe visible image; and a converting section which converts the imagedata used in output of the visible image in accordance with theconversion data stored in the storing section, wherein the conversiondata stored in the storing section has a conversion characteristic whichsuppresses a change in saturation in the visible image for pixelsbelonging to a predetermined color region.

In an image processing device relating to a second aspect of the presentinvention according to the first aspect, the predetermined color regionis a region in which a hue angle in the visible image falls within apredetermined range.

In an image processing device relating to a third aspect of the presentinvention according to the first aspect, the predetermined range is arange corresponding to skin (flesh) color.

In an image processing device relating to a fourth aspect of the presentinvention according to the first aspect, the predetermined color regionincludes at least one of a low saturation region where saturation in thevisible image is low, and a high saturation region where saturation inthe visible image is high.

In an image processing device relating to a fifth aspect of the presentinvention according to the first aspect, the predetermined color regionincludes at least one of a high lightness (luminosity) region wherelightness in the visible image is high, and a low lightness region wherelightness in the visible image is low.

In an image processing device relating to a sixth aspect of the presentinvention according to any one of the first to the fifth aspects, theconversion characteristic of the conversion data is set such that, thecloser to a center of the predetermined color region, the greater adegree of suppression of change in saturation in the visible image forpixels positioned within the predetermined color region in a vicinity ofa border thereof (a color gamut boundary).

In an image processing device relating to a seventh aspect of thepresent invention according to any one of the first to the fifthaspects, the conversion data is data which makes correspond a colorvalue before a saturation change and a color value after the saturationchange, when color values in the image data are changed such thatsaturation in the visible image changes.

In an image processing device relating to an eighth aspect of thepresent invention according to the first aspect, the conversioncharacteristic of the conversion data is set, on the basis of a colorreproduction gamut (range) in an output form of the visible image, suchthat a change in saturation is not saturated.

In an image processing device relating to a ninth aspect of the presentinvention according to the first aspect, the image processing devicefurther comprises: an instructing section for instructing a saturationchange amount, wherein a plurality of types of conversion data havingrespectively different saturation change amounts are stored in thestoring section, and the converting section converts image data byusing, among the plurality of types of conversion data, conversion datawhich corresponds to a saturation change amount which is instructed viathe instructing section.

In an image processing device relating to a tenth aspect of the presentinvention according to the ninth aspect, the saturation change amountsof the plurality of types of conversion data are respectively differentby greater than or equal to a predetermined value, and in a case inwhich the saturation change amount instructed via the instructingsection is a substantially intermediate value of saturation changeamounts corresponding to any of the plurality of types of conversiondata, the converting section, on the basis of conversion datacorresponding to (a) saturation change amount(s) which approximate(s)the instructed saturation change amount, determines, by interpolation,conversion data corresponding to the instructed saturation changeamount, and converts the image data by using the determined conversiondata.

In an image processing device relating to an eleventh aspect of thepresent invention according to the first aspect, a plurality of types ofoutput forms having respectively different color reproduction gamut(ranges) of the visible image are prepared as output forms of thevisible image, and on the basis of the color reproduction ranges of theplurality of types of output forms, the storing section stores aplurality of types of conversion data whose conversion characteristicsare set such that a change in saturation does not become saturated, andthe converting section converts the image data by using conversion datacorresponding to an output form which is used.

In an image processing device relating to a twelfth aspect of thepresent invention according to the first aspect, the image processingdevice further comprises: a designating section for designating a colorregion for which a change in saturation is to be suppressed; and agenerating section for generating conversion data of a conversioncharacteristic which suppresses a change in saturation in the visibleimage, for pixels belonging to at least one of the predetermined colorregion and a color region designated via the designating section.

In an image processing device relating to a thirteenth aspect of thepresent invention according to the first aspect, the image processingdevice further comprises: a display section for displaying an image; anda display control section for making the display section display animage expressed by image data which is converted by the convertingsection.

In an image processing method relating to a fourteenth aspect of thepresent invention, conversion data of a conversion characteristic whichchanges, in units of respective pixels and by a predetermined amount,saturation, in a visible image, of image data used in output of thevisible image, is stored, and the image data used in output of thevisible image is converted in accordance with the stored conversiondata, wherein the stored conversion data has a conversion characteristicwhich suppresses a change in saturation in the visible image for pixelsbelonging to a predetermined color region.

In order to achieve the above object, an image processing devicerelating to a fifteenth aspect of the present invention includes aconverting section for converting image data; a designating section fordesignating a conversion characteristic of gradation conversion of theimage data; and a control section for controlling a conversioncharacteristic of the converting section such that a gradation of theimage data is converted in accordance with a conversion characteristicwhich is designated via the designating section, and for one ofreconverting image data which is converted by the converting section andcontrolling the conversion characteristic of the converting section,such that changes in a ratio of a difference, of each of colorcomponents, with respect to gray of each pixel of the image data, whichchanges accompany conversion of the gradation of the image data inaccordance with the designated conversion characteristic, are corrected.

In an image processing device relating to a sixteenth aspect of thepresent invention according to the fifteenth aspect, the image data isimage data obtained by illuminating light onto a photographic film andconverting light, which has passed through a region at which an image isrecorded on the photographic film, into an electric signal by aphotoelectric conversion sensor.

In an image processing device relating to a seventeenth aspect of thepresent invention according to the fifteenth aspect, the control sectionone of reconverts the image data and controls the conversioncharacteristic of the converting section, in accordance with aconversion characteristic which satisfies the following expressions:R2′−(R2′+G2′+B2′)/3≈R2−(R2+G2+B2)/3,G2′−(R2′+G2′+B2′)/3≈G2−(R2+G2+B2)/3, andB2′−(R2′+G2′+B2′)/3≈B2−(R2+G2+B2)/3, where R2′, G2′, B2′are colorcomponent values of respective pixels of image data when image data,whose gradation has been converted in accordance with the designatedconversion characteristic, is converted, and R2, G2, B2 are colorcomponent values of respective pixels of image data when image data,whose gradation has not been converted, is converted.

In an image processing device relating to an eighteenth aspect of thepresent invention according to the fifteenth aspect, the control sectionincludes a multidimensional look-up table, and sets, in themultidimensional look-up table, conversion data which is set such thatchanges in a ratio of a difference, of each of color components, withrespect to gray of each pixel of the image data, which changes accompanyconversion of the gradation of the image data by the converting section,are corrected, and reconverts, by the multidimensional look-up table atwhich the conversion data is set, image data which is converted by theconverting section.

In an image processing device relating to a nineteenth aspect of thepresent invention according to the fifteenth aspect, the convertingsection converts the image data by a multidimensional look-up table, andthe control section controls the conversion characteristic of theconverting section by setting, in the multidimensional look-up table,conversion data of a conversion characteristic in which are superposedthe conversion characteristic designated via the designating section anda conversion characteristic which corrects changes in a ratio of adifference, of each of color components, with respect to gray of eachpixel of the image data at a time when gradation of the image data isconverted in accordance with the conversion characteristic designatedvia the designating section.

In an image processing device relating to a twentieth aspect of thepresent invention according to the fifteenth aspect, the convertingsection converts the image data by a multidimensional look-up table, andthe control section controls the conversion characteristic of theconverting section by setting, in the multidimensional look-up table,conversion data of a conversion characteristic which converts, inaccordance with the conversion characteristic designated via thedesignating section, only data corresponding to an achromatic colorportion among image data inputted to the multidimensional look-up table.

In an image processing device relating to a twenty-first aspect of thepresent invention according to the fifteenth aspect, a slope of theconversion characteristic is designated via the designating section asthe conversion characteristic of gradation conversion of the image data.

In an image processing device relating to a twenty-second aspect of thepresent invention according to the fifteenth aspect, when a range fromhighlight through shadow is divided into plural ranges, the conversioncharacteristic of gradation conversion of the image data is designatedindependently for each of the plural ranges via the designating section.

In an image processing device relating to a twenty-third aspect of thepresent invention according to the fifteenth aspect, the device furthercomprises a first storing section for storing plural types of conversioncharacteristics, wherein the conversion characteristic of gradationconversion of the image data is designated via the designating sectionby a specific conversion characteristic being selected from among theplural types of conversion characteristics stored in the first storingsection.

In an image processing device relating to a twenty-fourth aspect of thepresent invention according to the fifteenth aspect, the device furthercomprises a second storing section for storing a conversioncharacteristic designated via the designating section, wherein theconversion characteristic of gradation conversion of the image data isdesignated by correction of the conversion characteristic stored in thesecond storing section being designated via the designating section.

In an image processing method relating to a twenty-fifth aspect of thepresent invention, when a conversion characteristic of gradationconversion of image data is designated via a designating section, aconversion characteristic of conversion of the image data is controlledsuch that a gradation of the image data is converted in accordance witha conversion characteristic which is designated via a designatingsection, and image data which is converted is reconverted or theconversion characteristic of conversion of the image data is controlled,such that changes in a ratio of a difference, of each of colorcomponents, with respect to gray of each pixel of the image data, whichchanges accompany conversion of the gradation of the image data inaccordance with the designated conversion characteristic, are corrected.

In an image processing device relating to a twenty-sixth aspect of thepresent invention according to the fifteenth aspect, the control sectionreconverts the image data which is converted by the converting sectionor controls the conversion characteristic of the converting section,such that the ratio of the difference, of each of color components, withrespect to gray of each pixel of the image data, due to the conversionof the gradation of the image data in accordance with the designatedconversion characteristic, and a ratio of a difference, of each of colorcomponents, with respect to gray of each pixel of the image data, beforethe conversion of the gradation of the image data is performed, aresubstantially the same.

In an image processing method relating to a twenty-seventh aspect of thepresent invention according to the twenty-fifth aspect, the image datawhich is converted is reconverted or the conversion characteristic ofconversion of the image data is controlled, such that the ratio of thedifference, of each of color components, with respect to gray of eachpixel of the image data, due to the conversion of the gradation of theimage data in accordance with the designated conversion characteristic,and a ratio of a difference, of each of color components, with respectto gray of each pixel of the image data, before the conversion of thegradation of the image data is performed, are substantially the same.

In the first aspect of the present invention, conversion data of aconversion characteristic which changes, in units of respective pixelsand by a predetermined amount, saturation, in a visible image, of imagedata used in output of the visible image, is stored in the storingsection. The converting section converts the image data used in outputof the visible image in accordance with the conversion data stored inthe storing section. In this way, by outputting the visible image byusing the image data which has been converted, a visible image, whosesaturation has been changed by a predetermined amount, can be obtained.

The image data used in output of the visible image may be, for example,image data obtained by illuminating light onto a photographic film onwhich an image is recorded, and converting the light, which has passedthrough the photographic film, into an electrical signal by aphotoelectric converting section. Or, the image data may be image dataobtained by photographing a subject by a digital still camera, or imagedata which is generated by a computer. Further, examples of the outputform of the visible image are recording onto a recording material suchas photographic printing paper, display onto a display device such as adisplay, and the like.

The conversion characteristic which changes the saturation in thevisible image by a predetermined amount is determined as follows. Therelationship between color values (arbitrary physical amount valueswhich express colors; e.g., values expressing colors by using anarbitrary color system) in the image data, and color values in thevisible image at the time when the visible image is outputted by usingthe aforementioned image data. On the basis of this relationship, thecolor values in the original image are converted to the color values inthe visible image. By a predetermined amount, the saturations of thecolor values in the visible image after conversion are changed. Further,on the basis of the aforementioned relationship, the color values, afterthe saturation has been changed by the predetermined amount, areconcerted back into color values of the image data. In this way, colorvalues in the image data corresponding to the visible image whosesaturation has been changed by the predetermined amount, are determined,and can be determined on the basis of the relationship between the colorvalues of the image data and the color values of the original imagedata.

As in the seventh aspect of the present invention, the conversion datastored in the storing section may, for example, be data which makescorrespond a color value before a saturation change and a color valueafter the saturation change, when color values in the image data arechanged such that saturation in the visible image changes. For example,the color values themselves may be stored as conversion data, or afunction or the like representing the conversion characteristic may bestored as the conversion data.

Here, in the first aspect of the present invention, the conversion datawhich is stored in the storing section has a conversion characteristicwhich suppresses a change in saturation in the visible image for pixelsbelonging to a predetermined color region. The predetermined colorregion may be a color region which leads to a deterioration in imagequality of the visible image when the saturation in the visible imagechanges greatly. A color region defined in an arbitrary color space orarbitrary color coordinate may be used. Further, the predetermined colorregion may be prescribed on the basis of color values in the image data.However, it is preferable that the predetermined color region beprescribed on the basis of color values in the visible image.

By converting the image data by using the conversion data of theabove-described conversion characteristics, the visible image, which isoutputted by using the image data which has undergone conversion by theconverting section, is an image in which the change in saturation atportions corresponding to the predetermined color region is suppressedand the saturation at the other portions is changed by a predeterminedamount. In the first aspect of the invention, because the conversioncharacteristic by the converting section is prescribed by the conversiondata stored in the storing section, the conversion characteristic by theconverting section can be freely controlled.

In this way, in order to prevent a deterioration in image quality atportions, which deterioration accompanies the changing of the saturationin the visible image by a predetermined amount, the conversioncharacteristic is determined such that, for example, the change insaturation in the visible image is suppressed for respective pixelsbelonging to any of a plurality of color regions. In this way, a changein saturation at portions corresponding to any of the plural colorregions in the visible image can be suppressed. Or, as in the sixthaspect of the present invention, the conversion characteristic may beset such that, the closer to the predetermined color region, the greatera degree of suppression of change in saturation in the visible image forpixels positioned within the predetermined region in a vicinity of aborder. In this way, the finish in the vicinity of an outer edge of aportion corresponding to a predetermined color region in the visibleimage can be prevented from being unnatural. Accordingly, in accordancewith the first aspect of the present invention, the saturation of theimage (the visible image) can be adjusted without leading to adeterioration in image quality.

In the first aspect of the present invention, the predetermined colorregion may be stipulated, as in the second aspect for example, as aregion in which a hue angle in the visible image falls within apredetermined range. When the colors of the visible image are expressedby the L*a*b* color system which is the uniformly perceived color spacerecommended by the CIE (Commission Internationale de l'Eclairage), thehue angle H* is defined by following formula (1):

H*=tan⁻¹(b*/a*)·180/π  (1)

As described above, by stipulating the predetermined color region by thehue angle in the visible image, the change in saturation of pixels of aspecific hue in the visible image can be suppressed.

In the second aspect of the present invention, it is preferable that,for example, the predetermined range is a range corresponding to skincolor, as in the third aspect of the present invention. Note that therange corresponding to skin color is a range centered around hue angleH*≈45°. By making the predetermined color region of the presentinvention a range in which hue angles are values corresponding to skincolor as described above, the change in saturation of portions, in thevisible image, corresponding to the skin of persons can be suppressed. Adeterioration in image quality in portions, which deteriorationaccompanies the changing of the saturation of the visible image, caneffectively be suppressed.

Note that the predetermined range of the second aspect is not limited toa range corresponding to skin color as described above. For example,when the saturation of the entire image is greatly raised, portionscorresponding to the green of trees or grass existing within the imagehave an unnatural finish. The range corresponding to green color iscentered around hue angle H*=135°. Thus, the predetermined color regionrelating to the present invention may be a range in which the hue anglesare values corresponding to green color. Or, a range in which the hueangles are values corresponding to skin color and a range in which thehue angles are values corresponding to green color may both be used aspredetermined color regions of the present invention.

In the first aspect of the present invention, the predetermined colorregion relating to the invention may be, for example, prescribed by thesaturation in the visible image. For example, as in the fourth aspect ofthe present invention, it is preferable that the predetermined colorregion includes at least one of a low saturation region where saturationin the visible image is low, and a high saturation region wheresaturation in the visible image is high.

Namely, for example, when the saturation of the entire visible image israised uniformly regardless of the saturations at the respectiveportions, the saturations at portions where the saturation is a minimalvalue or near a minimal value (portions whose hue is a neutral color(gray) or is near a neutral color) are also raised. Thus, in the visibleimage after the saturation has been raised, the non-neutral colorcomponents included in these portions are emphasized such that itappears that there is color in these gray portions, and a problem arisesin that this is perceived as a deterioration in image quality. Further,at portions where the saturation is originally a maximum value or a neara maximum value, the saturation may rise so as to exceed the colorreproduction range of the visible image such that the rise in saturationis saturated (although this depends on the amount of increase insaturation and other parameters as well). Thus, a deterioration in imagequality, such as oversaturation or the like, may be caused.

Therefore, in accordance with the fourth aspect of the presentinvention, the change in saturation is suppressed at at least one of thelow saturation portions where the saturation is low in the visible imageand the high saturation portions where the saturation is high in thevisible image. Thus, even in a case such as when the saturation of thevisible image is greatly raised, a deterioration in image quality of atleast one of the low saturation portions and the high saturationportions in the visible image can be prevented.

In the fourth aspect of the present invention, the amount of change insaturation for the low saturation region can be set such that thesaturation suppression amount for pixels whose saturation is zero in thevisible image is a maximum (e.g., saturation change amount=0), and thesaturation suppression amount gradually decreases as the saturation inthe visible image of the pixels which are the object of saturationchanging increases. Further, for the saturation change amount for highsaturation regions as well, the saturation suppression amount for pixelsof the maximum saturation which can be expressed in the visible image(saturation in the outermost shell of the color reproduction range) is amaximum (e.g., the saturation change amount=0), and as the saturation inthe visible image of pixels which are the object of saturation changingdecreases, the saturation suppression amount gradually decreases.

In the first aspect of the present invention, the predetermined colorregion relating to the present invention may be prescribed by lightnessin the visible image. For example, as in the fifth aspect, it ispreferable that the predetermined color region includes at least one ofa high lightness region where lightness in the visible image is high,and a low lightness region where lightness in the visible image is low.

Namely, for example, when the saturation of the entire visible image israised uniformly regardless of the lightness at the respective portions,the saturations at portions where the lightness in the visible image isa maximum value or near a maximum value (highlight portions in thevisible image; regions which are usually white) are also raised. Thus,in the visible image after the saturation has been raised, thenon-neutral color components included in these portions are emphasizedsuch that it appears that there is color in the white regions, and aproblem arises in that this is perceived as a deterioration in imagequality. Further, at the high lightness portions and the low lightnessportions, it appears as if the saturation has changed greatly ascompared to the actual change in saturation. Thus, if the saturation ofthe entire visible image is raised uniformly, the change in saturationin the high lightness portions and the low lightness portions isperceived as a deterioration in image quality.

Therefore, in accordance with the fifth aspect of the present invention,the change in saturation is suppressed at at least one of the highlightness portions and the low lightness portions in the visible image.Thus, even in a case such as when the saturation of the visible image isgreatly raised, a deterioration in image quality of at least one of thehigh lightness portions and low lightness portions can be prevented.

In the fifth aspect of the present invention, the amount of change insaturation for the high lightness portions can be set such that thesaturation suppression amount for pixels of maximum lightness in thevisible image is a maximum (e.g., saturation change amount=0), and thesaturation suppression amount gradually decreases as the lightness, inthe visible image, of the pixels which are the object of saturationchanging decreases. Further, for the saturation change amount for lowlightness portions as well, the saturation suppression amount for pixelsof the lowest lightness in the visible image is a maximum (e.g., thesaturation change amount=0), and as the lightness, in the visible image,of pixels which are the object of saturation changing increases, thesaturation suppression amount gradually decreases.

In the invention of any of the first through fifth aspects, it ispreferable that, as in the sixth aspect of the present invention, theconversion characteristic of the conversion data is set such that, thecloser to the predetermined color region, the greater a degree ofsuppression of change in saturation in the visible image for pixelspositioned within the predetermined color region in a vicinity of aborder (i.e., the further from the predetermined color region, the lowerthe degree of suppression). In this way, the finish in the vicinity ofthe outer edge of portions corresponding to the predetermined colorregion in the visible image can be prevented from being unnatural.

However, the maximum saturation which can be expressed in the visibleimage (the saturation at the outermost shell in the color reproductionrange of the visible image) differs in accordance with the output formof the visible image. For example, in a case in which a visible image isoutputted by using image data which has undergone conversion by theconverting section, the saturation will be appropriate in a visibleimage which is outputted in a given output form, whereas, in a visibleimage which is outputted in another output form, the change insaturation may become saturated such that a deterioration in imagequality, such as oversaturation or the like, may occur.

In view of this fact, as in the eighth aspect of the present invention,it is preferable that the conversion characteristic of the conversiondata is set, on the basis of a color reproduction range in an outputform of the visible image, such that a change in saturation is notsaturated. Setting the conversion characteristic such that the change insaturation is not saturated can be realized as follows: saturationvalues at the outermost shell can be determined as the colorreproduction range for the output form of the visible image, and theconversion characteristic can be determined such that the saturationvalues in the visible image of the image data which has undergoneconversion by the converting section do not exceed the saturation valuesof the outermost shell.

Further, because the saturation values at the outermost shell (range)change in accordance with the hue or lightness, for example, a patch ofvarious hues, lightnesses and saturations may be output as the visibleimage, and the saturations in the visible image may be measured. In thisway, the relationship between, on the one hand, the hues and lightnessesin the visible image and, on the other hand, the saturation values inthe outermost shell can be determined in advance. The conversioncharacteristic can be set for each of the hues and lightnesses on thebasis of the determined relationship. In this way, a deterioration inimage quality, such as oversaturation or the like of the visible image,can be reliably prevented.

In the ninth aspect, a plurality of types of conversion data, whosesaturation change amounts are respectively different, are stored. Theimage data is converted by using the conversion data which correspondsto the saturation change amount instructed via the instructing section.Thus, if the operator instructs a saturation change amount via theinstructing section (e.g., an information input section such as akeyboard or a pointing device such as a mouse), the image data isconverted such that the saturation in the visible image is changed bythe instructed saturation change amount. Accordingly, a visible image,which has been adjusted to a saturation desired by the operator, caneasily be obtained.

In the ninth aspect, in a case in which it is possible for thesaturation change amount to be instructed via the instructing section inunits of extremely small change amounts, a large number of conversiondata whose saturation change amounts differ minutely can be stored inthe storing section as the conversion data. However, in such a case, aproblem arises in that an extremely large storage capacity is requiredin order to store the conversion data.

In consideration of this fact, in the tenth aspect of the presentinvention, it is preferable that different conversion data, whosesaturation change amounts are greater than or equal to a predeterminedvalue, are used as the plurality of types of conversion data, and that,in a case in which the saturation change amount instructed via theinstructing section is an intermediate value of a saturation changeamount corresponding to any of the plurality of types of conversiondata, the converting section, on the basis of conversion datacorresponding to a saturation change amount which approximates theinstructed saturation change amount, determines, by interpolation,conversion data corresponding to the instructed saturation changeamount, and converts the image data by using the determined conversiondata. In this way, the storage capacity needed for storing theconversion data can be reduced.

In a case in which a plurality of types of output forms havingrespectively different color reproduction ranges of the visible imageare prepared as output forms of the visible image, as in the eleventhaspect, it is preferable that, on the basis of the color reproductionranges of the plurality of types of output forms, the storing sectionstores a plurality of types of conversion data whose conversioncharacteristics are set such that a change in saturation does not becomesaturated, and the converting section converts the image data by usingconversion data corresponding to an output form which is used. In thisway, in an environment in which plural types of output forms areprepared as output forms of the visible image, the conversion data ofthe optimal conversion characteristic can be selectively used inaccordance with the output form of the visible image. A visible image,whose saturation is changed appropriately regardless of the output formof the visible image, can be obtained.

In the twelfth aspect of the invention, when a color region at which achange in saturation is to be suppressed is designated via thedesignating section, for the pixels belonging to at least one of thepredetermined color region and the color region designated via thedesignating section, conversion data of a conversion characteristicwhich suppresses the change in saturation in the visible image isgenerated. Thus, by the operator designating via the designating sectionan arbitrary color region at which the change in saturation is to besuppressed, conversion data of a desired conversion characteristic isautomatically generated.

In this way, even in a case such as when a color region at which thechange in saturation is to be suppressed newly arises, the change insaturation at that color region can be suppressed by that color regionbeing designated via the designating section. Thus, the saturation ofthe image can be changed at a desired conversion characteristic.

The designation of the color region at which the change in saturation isto be suppressed may be carried out by, for example, designating, by anumerical value (e.g., a numerical value which is normalized with theoutermost shell as a reference), a parameter such as hue angle,saturation, lightness or the like which prescribes the color region. Or,parameters such as the hue angle, saturation, lightness or the like maybe divided into plural numerical regions (e.g., high/intermediate/low).In this way, the color reproduction range can be divided in advance intoa plurality of divisional color regions, and any of these divisionalcolor regions may be designated as the region in which the saturationchange is to be suppressed.

In the thirteenth aspect of the present invention, by referring to theimage displayed on the display section, the operator can easily confirmwhether or not the saturation has been changed appropriately.

In the fourteenth aspect of the present invention, in the same way as inthe first aspect of the present invention, the saturation of the imagecan be adjusted without leading to a deterioration in image quality.

In the fifteenth aspect of the present invention, when a conversioncharacteristic of gradation conversion of image data is designated viathe designating section, the control section controls the conversioncharacteristic of the converting section which converts the image data,such that the gradation of the image data is converted in accordancewith the designated conversion characteristic. Further, the controlsection either reconverts the image data which has been subjected toconversion by the converting section, or controls the conversioncharacteristic of the converting section, such that changes in a ratioof a difference, of each of color components, with respect to the grayof each pixel of the image data, which changes accompany conversion ofthe gradation of the image data in accordance with the designatedconversion characteristic, are corrected.

In this way, the image data are corrected by reconverting the image dataor by controlling the conversion characteristic, such that a ratio of adifference, of each of the color components, with respect to the gray ofeach pixel of the image data whose gradation has been converted inaccordance with the designated conversion characteristic, is the same asor substantially the same as that of the image data before gradationconversion. If the ratios of the differences of the respective colorcomponents to the gray are the same or substantially equal, thesaturation and hue of each pixel is the same or substantially the same,even if the lightnesses are different. Thus, by correcting the imagedata as described above, changes in image quality, which changesaccompany conversion of the gradation, can be corrected accuratelyacross all of the regions from highlight regions through shadow regions.

As in the sixteenth aspect of the present invention, the image data ofthe fifteenth aspect may be image data obtained by illuminating lightonto a photographic film, and converting light, which has passed througha region at which an image is recorded on the photographic film, into anelectric signal by a photoelectric conversion sensor. Or, instead, theimage data may be image data obtained by photographing by a digitalstill camera or a digital video camera, or may be image data generatedby a computer, or the like.

In the fifteenth aspect of the present invention, reconverting of theimage data by the control section or control of the conversioncharacteristic of the converting section by the control section may berealized as follows as in the seventeenth aspect of the presentinvention. Concretely, the control section may reconvert the image dataor control the conversion characteristic of the converting section, inaccordance with a conversion characteristic which satisfies thefollowing expressions:R2′−(R2′+G2′+B2′)/3≈R2−(R2+G2+B2)/3,G2′−(R2′+G2′+B2′)/3≈G2−(R2+G2+B2)/3,B2′−(R2′+G2′+B2′)/3≈B2−(R2+G2+B2)/3,where R2′, G2′, B2′are color component values of respective pixels ofimage data when image data, whose gradation has been converted inaccordance with the designated conversion characteristic, is converted,and R2, G2, B2 are color component values of respective pixels of imagedata when image data, whose gradation has not been converted, isconverted.

The (R2′+G2′+B2′)/3 in the above expressions represents respective colorcomponent values of pixels whose hue is gray and whose lightness issubstantially the same as that of pixels whose color component valuesare R2′, G2′, B2′. The above (R2+G2+B2)/3 represents respective colorcomponent values of pixels whose hue is gray and whose lightness issubstantially the same as that of pixels whose color component valuesare R2, G2, B2. In accordance with the conversion characteristic whichsatisfies the above expressions, the image data is reconverted, or theconversion characteristic of the converting section is controlled. Inthis way, the saturation and the hue of each pixel of the image datawhose gradation has been converted can be made to be the same as orsubstantially the same as the saturation and hue of each pixel of theimage data before gradation conversion, regardless of the lightnesses ofthe respective pixels.

Further, correction of the change in the ratio of the difference, foreach color component, with respect to the gray of each pixel of theimage data can be realized by, for example, converting the image data byusing a multidimensional look-up table. For example, in a case in whichthe control section is structured so as to include a multidimensionallook-up table, as in the eighteenth aspect of the present invention, thecontrol section sets, in the multidimensional look-up table, conversiondata which is set such that changes in a ratio of a difference, of eachof color components, with respect to gray of each pixel of the imagedata, which changes accompany conversion of the gradation of the imagedata by the converting section, are corrected, and reconverts, by themultidimensional look-up table at which the conversion data is set,image data which has undergone conversion by the converting section.

In a case in which the converting section is structured so as to convertthe image data by a multidimensional look-up table, for example, as inthe nineteenth aspect of the present invention, the control sectioncontrols the conversion characteristic of the converting section bysetting, in the multidimensional look-up table, conversion data of aconversion characteristic in which are superposed a conversioncharacteristic designated via the designating section and a conversioncharacteristic which corrects changes in a ratio of a difference, ofeach of color components, with respect to gray of each pixel of theimage data at a time when gradation of the image data is converted inaccordance with the conversion characteristic designated via thedesignating section.

In a case in which the converting section is structured so as to convertthe image data by a multidimensional look-up table, for example, as inthe twentieth aspect of the present invention, the control sectioncontrols the conversion characteristic of the converting section bysetting, in the multidimensional look-up table, conversion data of aconversion characteristic which converts, in accordance with aconversion characteristic designated via the designating section, onlydata corresponding to an achromatic color portion among image datainputted to the multidimensional look-up table. In this case, among theimage data inputted into the multidimensional look-up table, thesaturations and the hues of the data corresponding to the chromaticcolor portions do not change. Thus, a change in image qualityaccompanying a change in gradation can be suppressed.

Various methods can be contemplated as methods for designating theconversion characteristic of the gradation conversion of the image data.For example, as in the twenty-first aspect of the present invention, inthe fifteenth aspect, the slope of the conversion characteristic may bedesignated via the designating section. In this case, although it isdifficult for the operator to designate a complex conversioncharacteristic via the designating section, the operator can easilydesignate simple conversion characteristics.

For example, as in the twenty-second aspect of the present invention,when a range from highlight through shadow is divided into pluralranges, the conversion characteristic may be designated independentlyfor each of the plural ranges by the designating section. In this case,the operator can accurately set a desired conversion characteristic.

Further, as in the twenty-third aspect of the present invention, a firststoring section for storing plural types of conversion characteristicsmay be provided, and the conversion characteristic of gradationconversion of the image data may be designated via the designatingsection by a specific conversion characteristic being selected fromamong the plural types of conversion characteristics stored in the firststoring section. In this case, a desired conversion characteristic maybe set in advance and stored in the first storing section. Thus, even incases such as when the desired conversion characteristic is a complexcharacteristic, designating of the conversion characteristic is easy.

Further, as in the twenty-fourth aspect of the present invention, asecond storing section for storing a conversion characteristicdesignated via the designating section may be provided, and theconversion characteristic of gradation conversion of the image data maybe designated by correction of the conversion characteristic stored inthe second storing section being designated via the designating section.In this case, a conversion characteristic, which the operator haspreviously designated independently via the designating section andwhich has been stored in the second storing section, can be called upvia the designating section and reused.

In an image processing method relating to a twenty-fifth aspect of thepresent invention, when a conversion characteristic of gradationconversion of image data is designated via a designating section, aconversion characteristic of conversion of the image data is controlledsuch that a gradation of the image data is converted in accordance witha conversion characteristic which is designated via a designatingsection, and image data which has undergone conversion is reconverted orthe conversion characteristic of conversion of the image data iscontrolled such that changes in a ratio of a difference, of each ofcolor components, with respect to gray of each pixel of the image data,which changes accompany conversion of the gradation of the image data inaccordance with the designated conversion characteristic, are corrected.Thus, in the same way as the invention of the first aspect, a change inimage quality which accompanies a change in gradation can be accuratelycorrected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a schematic structure of an imageprocessing system relating to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic structure of a colorreproduction conversion section.

FIG. 3A is a flowchart showing set-up processing which is carried out ata set-up computation section.

FIG. 3B is a flowchart showing set-up processing which is carried out ata set-up computation section.

FIG. 4 is a schematic diagram showing an example of an outermost shellof a color reproduction region in an output image in an L*a*b* colorspace, and an example of a relationship between RGB and L*a*b* at theoutermost shell.

FIG. 5A is a graph showing a relationship between hue angle andsaturation adjustment amount weighting factors in saturation adjustmentdata.

FIG. 5B is a graph showing a relationship between saturation andsaturation adjustment amount weighting factors in saturation adjustmentdata.

FIG. 5C is a graph showing a relationship between lightness andsaturation adjustment amount weighting factors in saturation adjustmentdata.

FIG. 6 is a graph showing an example of a relationship between a factorK used in correcting saturation adjustment data and a hue angle H* orsaturation C* or lightness L*, in a case in which addition of a colorregion which is an object of saturation change suppression is instructedby an operator.

FIG. 7 is a block diagram showing a schematic structure of an imageprocessing system relating to the embodiment of the present invention.

FIG. 8 is a flowchart showing the contents of set-up computationprocessing carried out at the set-up computation section.

FIG. 9A is a flowchart showing the contents of conversion conditionsetting processing.

FIG. 9B is a flowchart showing the contents of conversion conditionsetting processing.

FIG. 10 is an image diagram showing an example of a gradation conversioncondition correction screen.

FIG. 11A is a graph for explaining correction of gradation conversionconditions.

FIG. 11B is a graph for explaining correction of gradation conversionconditions.

FIG. 11C is a graph for explaining correction of gradation conversionconditions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a first embodiment of the present invention will bedescribed in detail with reference to FIGS. 1 through 6. FIG. 1 shows animage processing system 10 relating to the present embodiment. The imageprocessing system 10 relating to the present embodiment is provided witha film scanner 12, a media driver 14, and an image data receiving device16 as input devices for the input of image data. The image processingsystem 10 is provided with a CRT 20 for displaying an image, a laserprinter 22 for exposing and recording an image onto a photographicprinting paper, and a CD-R writing device 24 which writes image dataonto a CD-R, as output devices for the output of images.

At the film scanner 12, light is illuminated onto a photographic filmsuch as a negative film or a reversal film or the like. The light, whichpasses through the portion of the photographic film on which a filmimage is recorded (a negative image or a positive image which is madevisible by the photographic film being subjected to developingprocessing after a subject is photographed), is read by a reading sensor(a line sensor or an area sensor) such as a CCD or the like. The filmscanner 12 outputs the image data obtained by reading. Film images of,for example, 135 size photographic films, 110 size photographic films,photographic films on which a transparent magnetic layer is formed (240size photographic films, known as an APS films), or 120 size or 220 size(Brownie size) photographic films may be the object of reading by thefilm scanner 12.

Any of various types of information storing media, such as magneticdisks like floppy disks (FD), optical disks like CD-Rs, magnetoopticaldisks (MO), PC cards, smart media, or IC cards which can be loaded in adigital still camera (DSC) (hereinafter, collectively referred to as“digital camera cards”), or the like is set in the media driver 14. Themedia driver 14 reads out the image data stored on the set informationstoring medium and outputs the image data.

The image data receiving device 16 is connected to a computer networksuch as the Internet, receives RGB image data from an informationprocessing device (e.g., a personal computer (PC)) via the computernetwork, and outputs the received image data. The film scanner 12, themedia driver 14, and the image receiving device 16 are connected to animage data pre-processing section 26 of the image processing device 18.The image data outputted from these image data input devices is inputtedto the image data pre-processing section 26.

The image data pre-processing section 26 subjects the inputted imagedata to predetermined pre-processings which differ in accordance withthe source of the inputted image data. Examples of pre-processingscarried out on image data inputted from the film scanner 12 are darkcorrection, density conversion, shading correction, defective pixelcorrection, and the like. Examples of pre-processings carried out onimage data inputted from the media driver 14 are decompression of imagedata which has been compressed and recorded on an information storingmedium, image processings such as sharpness improvement, and the like.Examples of pre-processings carried out on image data inputted from theimage data receiving device 16 are decompression of compressed imagedata (e.g., image data in JPEG format) received by the image datareceiving device 16.

Output form designation information, which designates the output form ofthe image (whether the image should be exposed and recorded onto arecording material by the laser printer 22, or whether the image datashould be written onto a CD-R by the CD-R writing device 24), isattached to image data inputted from the film scanner 12, the mediadriver 14 and the image data receiving device 16. This output formdesignation information is inputted, in the state of being attached tothe image data, to various devices which will be described later.

The film scanner 12 relating to the present embodiment reads each filmimage recorded on a photographic film two times, each time at adifferent resolution. In the first reading (hereinafter, “prescanning”)which is carried out at a relatively low resolution, reading is carriedout under reading conditions which are determined so as to not causeproblems such as saturation of the accumulated charge of the readingsensor, even if the density of the film image is extremely low (forexample, even in the case of an underexposed negative image of anegative film).

A prescan memory 28 and a fine scan memory 30 are connected to the imagedata pre-processing section 26. A first image processing section 32 anda set-up computation section 34 are connected to the prescan memory 28.A second image processing section 36 is connected to the fine scanmemory 30. When low resolution image data is inputted to the image datapre-processing section 26 from the film scanner 12 due to prescanningbeing carried out, the image data pre-processing section 26 subjectsthis low resolution image data to pre-processings, and thereafter,outputs the data to the prescan memory 28.

The image data pre-processing section 26 outputs, to the prescan memory28 and the fine scan memory 30, the image data inputted from the mediadriver 14 and the image data inputted from the image data receivingdevice 16. The image data which is outputted to the prescan memory 28 isoutputted to the prescan memory 28 after being converted into image dataof a low resolution equivalent to the resolution of the low resolutionimage data obtained by prescanning. The low resolution image dataoutputted to the prescan memory 28 is inputted to the set-up computationsection 34 via the prescan memory 28.

The set-up computation section 34 and the first image processing section32 can be realized by a single microcomputer in which the CPU, ROM, RAM,and input/output port are connected together via a bus, and in which astorage device such as a hard disk device (HDD) is connected to theinput/output port. By making this microcomputer execute predeterminedprograms, the microcomputer can be made to function as both the firstimage processing section 32 and the set-up computation section 34.

In a case in which the low resolution image data inputted via theprescan memory 28 is image data obtained by prescanning by the filmscanner 12, on the basis of this low resolution image data, the set-upcomputation section 34 computes an image characteristic amount such asdensity or the like, and determines reading conditions for the time thatthe film scanner 12 is to read the prescanned photographic film again,this time at a relatively high resolution (hereinafter, “finescanning”), and outputs the determined reading conditions to the filmscanner 12.

On the basis of the inputted low resolution image data, the set-upcomputation section 34 automatically determines by computation (set-upcomputation) processing conditions for various types of processings tobe carried out by the second image processing section 36 on the highresolution image data of the same image outputted from the image datapre-processing section 26 via the fine scan memory 30 to the secondimage processing section 36 (the image data inputted from the finescanner 12 due to the fine scan, or the image data inputted from themedia driver 14, or the image data inputted from the image datareceiving device 16). The set-up computation section 34 also informs thefirst image processing section 32 of these determined processingconditions.

Examples of the image processings carried out at the second imageprocessing section 36 are various processings for improving the imagequality of the output image such as image gray balance adjustment,density adjustment, gradation control, hypertone processing forcompressing the gradation of the ultra-low frequency luminancecomponents of the image, hypersharpness processing for enhancingsharpness while suppressing graininess, and the like. Further, it isalso possible to carry out image processings such as image processingfor intentionally changing the image gradation (e.g., image processingto make the output image have a portrait finish), image processing formanipulating the image (e.g., image processing for making a person inthe original image appear thinner in the main image), or the like.

On the basis of the processing conditions relayed from the set-upcomputation section 34, for the low resolution image data stored in theprescan memory 28, the first image processing section 32 carries out, onthe low resolution image data, image processings which are equivalent tothe image processings carried out at the second image processing section36 on the high resolution image data, and generates simulation imagedata. A color reproduction conversion section 38 and a CRT 20 areconnected in that order to the first image processing section 32. Thesimulation image data generated at the first image processing section 32is outputted to the color reproduction conversion section 38. Note thatthe CRT 20 corresponds to the display section of the present invention.

As shown in FIG. 2, the color reproduction conversion section 38 isstructured by a look-up table (LUT) 40 for density conversion, aselector 42, a three-dimensional look-up table (3D-LUT) 44 forsaturation adjustment, and a selector 46 being connected in that order.The LUT 40 for density conversion is for converting the density of theinputted image data such that the density of the image expressed by theinputted image data is appropriately reproduced in the output image (theimage which is made visible on a photographic printing paper in theoutput form of recording images on a photographic printing paper, or animage displayed on the CRT 20 by using the recorded image data in theoutput form of recording image data on a CD-R; such images correspond tothe visible image of the present invention). The 3D-LUT 44 forsaturation adjustment is for adjusting the saturation of the outputimage in a case in which adjustment of saturation is instructed. Theoutput ends of the selector 46 are connected to the CRT 20, the laserprinter 22, and the CD-R writing device 24.

The 3D-LUT 44 for saturation adjustment and the set-up computationsection 34, which sets saturation adjustment data (to be described indetail later) in the 3D-LUT 44 for saturation adjustment, correspond tothe converting section of the present invention.

The simulation image data which is outputted from the first imageprocessing section 32 is subjected to color reproduction conversionprocessing (which will be described in detail later) such as densityconversion or the like by the color reproduction conversion section 38,and thereafter, is outputted to the CRT 20 and displayed on the CRT 20as a simulation image (output image). The finish and the like of theoutput image displayed on the CRT 20 can thus be verified by anoperator.

A key correction input section 48 is connected to the set-up computationsection 34. The key correction input section 48 may be formed by, forexample, a keyboard or a mouse which is connected to the input/outputport of the microcomputer. The operator who is verifying the outputimage displayed on the CRT 20 operates the key correction input section48 so as to input the results of verification. When the operator hasdecided on the processing conditions through this verification, theset-up computation section 34 informs the second image processingsection 36 of these decided-on processing conditions. Note that the keycorrection input section 48 corresponds to both the instructing sectionand the indicating section of the present invention.

The second image processing section 36 is provided with plural types ofimage processing circuits for carrying out the various types of imageprocessings mentioned previously. When the high resolution image data isinputted from the image data pre-processing section 26 via the fine scanmemory 30, the second image processing section 36 subjects the inputtedhigh resolution image data to various types of image processings inaccordance with the processing conditions which have been relayed fromthe set-up computation section 34. The second image processing section36 is connected to the color reproduction conversion section 38. Theimage data outputted from the second image processing section 36 issubjected to color reproduction conversion processing at the colorreproduction conversion section 38, and is then outputted to the laserprinter 22 or the CD-R writing device 24. The image data is used torecord an image onto a photographic printing paper by the laser printer22, or is written onto a CD-R by the CD-R writing device 24.

The laser printer 22 is equipped with RGB laser light sources. The RGBlaser lights emitted from the laser light sources are modulated on thebasis of the image data inputted from the image processing device 18,and are deflected by a deflecting section such as a polygon mirror orthe like so as to be scanned onto a photographic printing paper. Animage is thereby exposed and recorded onto the photographic printingpaper. The photographic printing paper on which the image has beenexposed and recorded is sent to a processor section (not shown) wherethe photographic printing paper is subjected to various processings suchas color developing, bleaching fixing, washing, and drying. In this way,the image which has been exposed and recorded on the photographicprinting paper is made visible.

Next, operation of the present embodiment will be described withreference to the flowchart in FIGS. 3A and 3B which show the set-upprocessing executed at the CPU of the set-up computation section 34.This set-up processing is executed by (the CPU of) the set-upcomputation section 34 each time the low resolution image data of asingle image is stored in the prescan memory 28.

In step 100, the low resolution image data stored in the prescan memory28 is fetched, and image data analysis including processings suchextraction of the main portions in the image (e.g., the regionscorresponding to the faces of persons (face regions)), computation ofvarious types of image characteristic amounts, and the like, is carriedout. In step 102, on the basis of the results of analysis of the imagedata in step 100, the optimal processing conditions for the imageprocessing to be carried out at the second image processing section 36on the high resolution image data are computed, and the first imageprocessing section 32 is informed of these computed processingconditions.

Density conversion data, which is for converting, at the LUT 40 fordensity conversion, the density of the image data such that the densityof the image expressed by the image data inputted to the colorreproduction conversion section 38 can be reproduced appropriately inthe output image, is stored in a storage portion 50 (formed by an HDD)of the set-up computation section 34.

The following three output forms are prepared as the image output formsin the present embodiment: displaying the image onto the CRT 20 (monitordisplay), recording the image onto a photographic printing paper by thelaser printer 22 (print output), and writing the image data onto a CD-Rby the CD-R writing device 24 (CD-R writing). However, because the imagedata written onto a CD-R is usually used in display onto a CRT monitor,when displaying the image data on the CRT monitor, it is preferable todisplay the image data on the CRT monitor at a preferable image qualitywithout subjecting the image data to any particular post-processings. Asa result, in the present embodiment, the density conversion data formonitor display and the density conversion data for CD-R writing areused in common, and two types of density conversion data, which are datafor print output and data for monitor display/CD-R writing, are storedin the storage portion 50.

The processing at this time is processing for displaying the simulationimage data, which was outputted from the first image processing section32, on the CRT 20 as an image (output image), and for the operator toverify the finish of the output image by using the output image. Thus,in the subsequent step 104, the density conversion data for monitordisplay/CD-R writing is read out from the storage portion 50, and is setin the LUT 40 for density conversion of the color reproductionconversion section 38.

On the other hand, because the 3D-LUT 44 for saturation adjustment is anLUT which is used when the operator instructs adjustment of thesaturation of the output image, in step 104, the selector 42 is switchedsuch that the image data inputted to the selector 42 from the LUT 40 fordensity conversion is inputted directly to the selector 46, and theselector 46 is switched such that the image data inputted to theselector 46 is outputted to the CRT 20.

In step 106, on the low resolution image data stored in the prescanmemory 28, various types of image processings are carried out by thefirst image processing section 32, and color reproduction conversionprocessing (in this case, only density conversion processing by the LUT40 for density conversion) is carried out by the color reproductionconversion section 38.

In this way, the first image processing section 32 fetches the lowresolution image data from the prescan memory 28, and on the basis ofthe processing conditions relayed by the processing of step 102,subjects the low resolution image data to image processings which areequivalent to the image processings carried out at the second imageprocessing section 36 on the high resolution image data, and generatessimulation image data. The simulation image data generated by the firstimage processing section 32 is density-converted by the LUT 40 fordensity conversion of the color reproduction conversion section 38, suchthat the “appearances” of the image displayed on the CRT 20 and theprint to be obtained by exposing and recording the image onto aphotographic printing paper match.

In step 108, the image data which has been subjected to colorreproduction processing by the color reproduction conversion section 38is outputted to the CRT 20. An image expressed by the image data isthereby displayed on the CRT 20 as an output image. A message requestingthat the operator verify the output image displayed on the CRT 20 isalso displayed on the CRT 20, so that the operator is made to verify thefinish and the like of the respective portions of the output imagedisplayed on the CRT 20.

When the output image is displayed on the CRT 20 and verification of theoutput image is requested, the operator visually confirms the outputimage displayed on the CRT 20, and verifies whether or not the imagequality of the output image is appropriate, i.e., whether the processingconditions computed at the set-up computation section 34 areappropriate, and whether the saturation of the output image isappropriate. The operator inputs information expressing the results ofverification via the key correction input section 48.

When the operator inputs information expressing the results ofverification via the key correction input section 48, the routine moveson to step 110 where it is judged whether the information expressing theresults of verification which the operator inputted via the keycorrection input section 48 is information meaning that the image hasbeen verified to be satisfactory (“verification OK”). In a case in whichinformation meaning “verification OK” has been inputted, the answer tothe above determination is affirmative, and the routine moves on to step130. However, in a case in which information instructing correction ofthe image processing conditions or information instructing adjustment ofthe saturation of the image is inputted as the information expressingthe results of verification, it is judged that the results ofverification by the operator are that the image is unsatisfactory(“verification NG (no good)”), and the routine moves on to step 112.

In step 112, it is judged whether the information expressing theinputted results of verification is information instructing adjustmentof the saturation of the image. In a case in which informationinstructing correction of the image processing conditions has beeninputted, the determination in step 112 is negative, and the routinemoves on to step 114. In step 114, the image processing conditionscomputed in previous step 102 are corrected in accordance with theinputted instructions, and the first image processing section 32 isinformed of the corrected processing conditions. Thereafter, the routinereturns to step 106.

In this way, at the first image processing section 32, processing forregenerating the simulation image data is carried out in accordance withthe corrected processing conditions, and the regenerated simulationimage data is subjected to density conversion by the LUT 40 for densityconversion of the color reproduction conversion section 38, and thenoutputted to the CRT 20. In this way, an output image is displayed onthe CRT 20 on the basis of the processing conditions which have beencorrected in accordance with the inputted correction instructions. Dueto the operator visually confirming the output image displayed on theCRT 20 this time, the operator can easily judge whether or not thecontents of the inputted correction instructions are appropriate.

On the other hand, in a case in which it is determined that thesaturation of the output image displayed on the CRT 20 is inappropriate,the operator inputs, via the key correction input section 48,information instructing adjustment of the saturation of the image(specifically, information instructing the saturation adjustment amountor other information). Note that, in the present embodiment, adjustmentof the saturation is possible only in the direction of increasing thesaturation, and the saturation adjustment amount instructed by theoperator is an amount of increase in the saturation. When the operatorinputs information instructing adjustment of the saturation, the answerto the determination in step 110 is negative and the answer to thedetermination in step 112 is affirmative, and the routine moves on tostep 116.

In steps from step 116 on, processing for adjusting the saturation ofthe image is carried out by the 3D-LUT 44 for saturation adjustment ofthe color reproduction conversion section 38. However, before thisprocessing is described, an explanation will first be given of thesaturation adjustment data which is set in the 3D-LUT 44 for saturationadjustment at the time when adjustment of the saturation of the image iscarried out by the 3D-LUT 44 for saturation adjustment.

Saturation adjustment data, which is for adjustment of the saturation inthe output image by the 3D-LUT 44 for saturation adjustment, is stored(registered) in advance in the storage portion 50 (which is formed froman HDD) of the set-up computation section 34. This saturation adjustmentdata is data which makes the RGB values of the individual pixels of theimage data before saturation adjustment and the RGB values of theindividual pixels of the image data after saturation adjustmentcorrespond to one another. The saturation adjustment data changes thesaturation in the output image by using as a reference a saturationadjustment amount ΔC for each individual pixel, and has a conversioncharacteristic which, for pixels belonging to a predetermined colorregion, converts the image data such that the change in saturation issuppressed. The saturation adjustment data corresponds to the conversiondata relating to the present invention, and the storage portion 50corresponds to the storing section relating to the present invention.

As shown as an example in following Table 1, plural types of saturationadjustment data D are prepared in accordance with the output forms ofimages and the values of the saturation adjustment amounts ΔC forimages. (In Table 1, the saturation adjustment data corresponding to“print output” at the time when the saturation adjustment amount ΔC isincreased by x each time are denoted by D_(P1), D_(P2), D_(P3), . . . ,and the saturation adjustment data corresponding to “monitordisplay/CD-R writing” at the time when the saturation adjustment amountΔC is increased by x each time are denoted by D_(M1), D_(M2), D_(M3), .. . . ) These plural types of saturation adjustment data D are stored inthe storage portion 50. TABLE 1 Saturation Adjustment Data Tablesaturation adjustment amount ΔC +x +2x +3x . . . output print D_(P1)D_(P2) D_(P3) . . . form output monitor D_(M1) D_(M2) D_(M3) . . .display/CD-R writing

The saturation adjustment data is set, for example, as will be describedhereinafter. Namely, first, the relationship between the density values(hereinafter, “RGB values”) of the respective color components of theimage data (RGB in the present embodiment), and the L*a*b* in the outputimage at the time the image is outputted by using that image data isdetermined for each output form (L*a*b* is the color system recommendedas a uniformly perceived color space by CIE, wherein L* is a lightnessindex, and a*b* are the perceived chromaticities). Specifically, patchesof various colors (colors having different combinations of RGB values)are outputted as images, and the L*a*b* of each patch in the outputimage is measured by a measuring device for each output form.

Then, for colors for which patches are not prepared, for each of theoutput forms, the relationship between the RGB values of the image dataand the L*a*b* values in the output image is determined by interpolationcomputation. Thus, the relationships between the RGB values of the imagedata and the L*a*b* values in the output image are determined for theentire color reproduction region of the output image. In this way, asshown as an example in FIG. 4, the relationships between the RGB valuesof the image data and the L*a*b* values in the output image at anoutermost shell (points at which one color among RGB is a minimum value(e.g., zero) or a maximum value (e.g., 255 when the density is expressedby 8-bit data)) of the color reproduction range in the output image canbe determined at the same time.

Next, for all combinations of the RGB values of the image data, on thebasis of the relationships determined as described above, the RGB valuesare converted into L*a*b* values in the output image. Further,conversion of the L*a*b*, which are obtained by conversion, into L*C*H*is carried out for each of the output forms. H* is the hue angle and isdetermined by formula (1) which was previously put forth herein. C* issaturation and can be determined from the perceived chromaticities a*b*in accordance with the formula C*={square root}(a*²+b*²). In this way,the respective saturations C* in the output image when the image isoutput in each of the output forms can be determined, for all of thecombinations of RGB values of the image data.

Next, among the L*C*H* in the output image corresponding to all of thecombinations of RGB values of the image data, the values of thesaturations C* are adjusted, with reference to the predeterminedsaturation adjustment amount ΔC, such that the desired change insaturation arises in the output image. In the present embodiment,saturation adjustment is carried out by respectively converting thesaturations C* in the output image, which correspond to all of thecombinations of RGB values of the image data, in accordance withfollowing expression (2):C*′←C*+a(ΔC)wherein C* represents the saturation before saturation adjustment, C*′represents the saturation after saturation adjustment, ΔC is thesaturation adjustment amount, and α is a weighting factor of thesaturation adjustment amount. As is clear from the above formula, thesaturation adjustment amount varies in accordance with the value of theweighting factor a of the saturation adjustment amount.

In the present embodiment, the weighting factor a of the saturationadjustment amount is the product of a first weighting factor α₁, asecond weighting factor α₂, and a third weighting factor α₃. (Instead,the minimum value of the weighting factors α₁ through α₃ may be used asthe weighting factor α.) The first through third weighting factors α₁through α₃ are determined as described hereinafter.

Namely, the first weighting factor α₁ is a function of the hue angle H*in the output image (α₁=f(H*)), and, for example, the relationship withthe hue angle H* is predetermined as shown in FIG. 5A. The pattern ofthe first weighting factor α₁ shown in FIG. 5A is determined such that,in a predetermined range (e.g., a range corresponding to skin color)which is centered around hue angle H*≈45°, the first weighting factor α₁is zero or a value near zero, and the first weighting factor α₁increases the more that the hue angle H* moves away from thepredetermined range in a vicinity of the predetermined range. Note thatthe color region corresponding to the aforementioned “predeterminedrange which is centered around hue angle H*≈45°” corresponds to thepredetermined color region in the present invention.

The second weighting factor α₂ is a function of the normalizedsaturation in the output image (α₂=f(normalized saturation)). Forexample, the relationship with the normalized saturation ispredetermined as shown in FIG. 5B. The normalized saturation is a valuein which the saturation C* is normalized with reference to thesaturation C* at the outermost shell of the color reproduction region ofthe output image. The pattern of the second weighting factor α₂ shown inFIG. 5B is determined such that, when the normalized saturation is zero,the second weighting factor α₂ is zero, and in a range in which thenormalized saturation is less than a predetermined value, the slope ofthe increase in the value of the second weighting factor α₂ with respectto the increase in the normalized saturation is extremely small, and ina range in which the normalized saturation is less than thepredetermined value, the second weighting factor α₂ is zero or a valuenear zero, and in a vicinity of a range less than the predeterminedvalue, the second weighting factor α₂ gradually increases as thenormalized saturation moves away from the range.

The pattern of the second weighting factor α₂ is such that, when thenormalized saturation is a maximum value (a saturation corresponding tothe outermost shell), the second weighting factor α₂ is zero, and thevalue of the second weighting factor α₂ increases as the normalizedsaturation decreases from the maximum value. Thus, the pattern of thesecond weighting factor α₂ is determined such that, in a range in whichthe normalized saturation is a maximum value or near a maximum value,the second weighting factor α₂ is zero or a value near zero. Note thatthe color region corresponding to the aforementioned “range in which thenormalized saturation is less than a predetermined value” and the colorregion corresponding to the “range in which the normalized saturation isa maximum value or near a maximum value” correspond to the predeterminedcolor regions relating to the present invention.

The third weighting factor α₃ is a function of the normalized lightnessin the output image (α₃=f(normalized lightness)). For example, therelationship with the normalized lightness is predetermined as shown inFIG. 5C. The normalized lightness is a value in which the lightnessindex L* is normalized with reference to the maximum value of thelightness indices L* in the output image (i.e., with reference to thelightness index L* in the output image corresponding to the RGB value(e.g., R, G, B=255) at which the lightness of the image data is amaximum). The pattern of the third weighting factor α₃ shown in FIG. 5Cis determined such that, when the normalized lightness is zero, thethird weighting factor α₃ is zero, and as the normalized lightnessincreases from zero, the value of the third weighting factor α₃increases, and thus, in a range in which the normalized lightness iszero or a value near zero, the third weighting factor α₃ is zero or avalue near zero.

The pattern of the third weighting factor α₃ is determined such that,when the normalized lightness is a maximum lightness, the thirdweighting factor α₃ is zero, and in a range in which the normalizedlightness is greater than or equal to a predetermined value near themaximum lightness, the slope of the increase in the value of the thirdweighting factor α₃ with respect to a decrease in the normalizedlightness is extremely small, and in a range in which the normalizedlightness is greater than or equal to the predetermined value, the thirdweighting factor α₃ is zero or a value near zero, and in a vicinity ofthe range greater than or equal to the predetermined value, the thirdweighting factor α₃ gradually increases as the normalized lightnessmoves away from the range.

Note that the color region corresponding to the aforementioned “range inwhich the normalized lightness is zero or a value near zero” and thecolor region corresponding to the “range in which the normalizedlightness is greater than or equal to a predetermined value” correspondto the predetermined color regions relating to the present invention.

For the saturations C* in the output image corresponding to all of thecombinations of RGB values of the image data, first through thirdweighting factors α₁ through α₃ are derived and saturation adjustmentweighting factors α are respectively determined from the hue angle H*,the normalized saturation, and the normalized lightness in the outputimage. By substituting the determined weighting factors α and saturationadjustment amounts ΔC into above formula (2), the saturations C* in theoutput image corresponding to all of the combinations of RGB values ofthe image data are respectively adjusted.

Then, the values of L*C*H* after the saturation C* has been adjusted areconverted back into values of L*a*b* of the output image, and the valuesof L*a*b* are then converted back into RGB values of the image data. Inthis way, for all combinations of the RGB values of the image data, RGBvalues at the time the saturations C* are converted with reference tothe saturation adjustment amounts ΔC in the output image and on thebasis of the weighting factors α₁ through α₃, are respectively obtained.

The saturation adjustment data can be obtained by making the RGB valuesafter saturation adjustment and the RGB values before saturationadjustment correspond to each other. In this way, the saturations in theoutput image are converted by using, as a reference, the saturationadjustment amounts ΔC for each of the pixels. Further, for the pixelsbelonging to predetermined color regions (i.e., the color regioncorresponding to a predetermined range centered around hue angle H*≈45°,the color region corresponding to a range in which the normalizedsaturation is less than a predetermined value, the color regioncorresponding to a range in which the normalized saturation is a maximumvalue or near a maximum value, the color region corresponding to a rangein which the normalized lightness is zero or near zero, and the colorregion corresponding to a range in which the normalized lightness is apredetermined value or more), saturation adjustment data of a conversioncharacteristic, which converts image data such that the change insaturation is suppressed, can be obtained.

The 3D-LUT 44 for saturation adjustment can be structured such that allof the RGB values after saturation adjustment corresponding to all ofthe combinations of RGB values of the image data are stored assaturation adjustment data, and when an RGB value before saturationadjustment is inputted, the corresponding RGB value after saturationadjustment is merely read out and outputted. However, in this case, thedata amount of the respective saturation adjustment data is extremelylarge, and thus, a problem arises in that a memory having an extremelylarge storage capacity is required for the 3D-LUT 44 for saturationadjustment and the storage portion 50.

As a result, in a case in which the RGB values after saturationadjustment, which correspond to all of the combinations of RGB values ofthe image data, are appropriately thinned to form the saturationadjustment data, and the RGB values after saturation adjustment, whichcorrespond to the inputted RGB values before saturation adjustment, arenot stored in the 3D-LUT 44 for saturation adjustment as saturationadjustment data, it is preferable that the RGB values after saturationadjustment corresponding to the RGB values before saturation adjustmentare determined by interpolation computation from the RGB values aftersaturation adjustment which are stored as the saturation adjustmentdata. In this way, the storage capacity required for the 3D-LUT 44 forsaturation adjustment and the storage portion 50 can be reduced.

In step 116 of the set-up processing (FIGS. 3A and 3B), the saturationadjustment amount instructed by the operator operating the keycorrection input section 48 is sensed. In subsequent step 118, among thesaturation adjustment data stored in the storage portion 50, thesaturation adjustment data, which corresponds to the “monitordisplay/CD-R writing” and whose corresponding saturation adjustmentamount ΔC matches the saturation adjustment amount which is instructed,is fetched.

In the present embodiment, the saturation adjustment data for each timethe saturation adjustment amount ΔC increases by x are stored. Thus,cases may arise in which saturation adjustment data, whose correspondingsaturation adjustment amount ΔC matches the saturation adjustment amountwhich has been instructed, does not exist. However, in such a case, instep 118, a plurality of saturation adjustment data, whose correspondingsaturation adjustment amounts ΔC are near the saturation adjustmentamount which has been instructed, are fetched.

This step 118, step 128 which will be described later, and the 3D-LUT 44for saturation adjustment correspond to the converting section recitedin the ninth and eleventh aspects.

In subsequent step 120, a determination is made as to whether saturationadjustment data, whose corresponding saturation adjustment amount ΔCmatches the saturation adjustment amount which was instructed, is storedin the storage portion 50, i.e., whether it is necessary to compute byinterpolation the saturation adjustment data. When the answer to thedetermination is negative, the routine moves on to step 124 without anyprocessings being carried out. However, in a case in which a pluralityof saturation adjustment data are fetched in step 118, the answer to thedetermination in step 120 is affirmative, and the routine moves on tostep 122. In step 122, on the basis of the fetched plurality ofsaturation adjustment data, saturation adjustment data whosecorresponding saturation adjustment amount ΔC matches the instructedsaturation adjustment amount, is determined by interpolationcomputation. This step 122 corresponds to the converting section recitedin the tenth aspect.

In next step 124, a determination is made as to whether a color regionfor which a change in saturation should be suppressed has beenindicated. Indication of the color region will be explained later. Ifthe answer to the determination in step 124 is negative, the routinemoves on to step 128. In step 128, the instructed saturation adjustmentdata is set in the 3D-LUT 44 for saturation adjustment, and the selector42 is switched such that the image data inputted to the selector 42 fromthe LUT 40 for density conversion is inputted to the 3D-LUT 44 forsaturation adjustment.

In this way, the simulation image data is regenerated at the first imageprocessing section 32. The density of the regenerated simulation imagedata is converted by the LUT 40 for density conversion of the colorreproduction conversion section 38, and thereafter, the simulation imagedata is inputted to the 3D-LUT 44 for saturation adjustment. The imagedata which is inputted to the 3D-LUT 44 for saturation adjustment isconverted, by the 3D-LUT 44 for saturation adjustment, into image dataafter saturation adjustment for each pixel, and is outputted to the CRT20 and displayed on the CRT 20 as an output image whose saturation hasbeen adjusted. Note that the processing of displaying the output imageon the CRT 20 at this time (step 108) corresponds to the display controlsection recited in the thirteenth aspect.

As described above, the saturation adjustment data set in the 3D-LUT 44for saturation adjustment is data which is set on the basis of the colorreproduction range of the output image displayed on the CRT 20(specifically, on the basis of the relationship between the RGB valuesof the image data and the L*a*b* values (L*C*H* values) in the outputimage displayed on the CRT 20). The corresponding saturation adjustmentamounts ΔC match the saturation adjustment amounts which have beeninstructed. The saturation adjustment data has a conversioncharacteristic which converts image data such that a change insaturation is suppressed for pixels belonging to predetermined colorregions (i.e., the color region corresponding to a predetermined rangecentered around hue angle H*≈45°, the color region corresponding to arange in which the normalized saturation is less than a predeterminedvalue, the color region corresponding to a range in which the normalizedsaturation is a maximum value or near a maximum value, the color regioncorresponding to a range in which the normalized lightness is zero ornear zero, and the color region corresponding to a range in which thenormalized lightness is a predetermined value or more).

Thus, at the output image displayed on the CRT 20, on the whole, in acase in which a change in saturation (an increase in saturation)corresponding to the saturation adjustment amount instructed by anoperator arises and the apparent vividness of the output image improvesand there are portions corresponding to the skin of a human in theoriginal image, changes in saturation of these portions in the outputimage are suppressed. Thus, a deterioration in image quality of theoutput image, such as, for example, redness or pimples of a person'sface being emphasized more than needed, can be prevented.

Further, in a case in which there exist neutral color portions in theoriginal image (portions whose hue is a neutral color or near a neutralcolor), the neutral colored portions can be prevented from becomingcolored in the output image. Further in a case in which there exist highsaturation portions in the original image (portions whose saturation isa maximum value or near a maximum value), oversaturation (the change insaturation being saturated) can be prevented from occurring at the highsaturation portions in the output image, and the saturation of thehighlight portions (high lightness portions) and shadow portions (lowlightness portions) of the original image can be prevented from changinggreatly in the output image as compared to the instructed saturationadjustment amount.

As is clear from FIGS. 5A through 5C as well, the conversioncharacteristic of the saturation adjustment data set in the 3D-LUT 44for saturation adjustment is determined such that, in a vicinity of apredetermined color region which is the object of saturation changesuppression, the extent of the suppression of a change in saturationdecreases as the distance from the predetermined color region increases.Thus, in a case in which there is a portion belonging to thepredetermined color region in the original image, there is no unnaturalfinish in the output image, such as portions, in which the saturationadjustment amount suddenly changes, arising at the periphery of thisportion.

Due to the operator visually confirming the output image which isdisplayed this time on the CRT 20, the operator verifies whether or notthe image quality of the output image has been appropriately improved bythe instructed saturation adjustment. Then, for example, if the operatorjudges that the saturation adjustment amount is inappropriate, theoperator inputs, via the key correction input section 48, informationfor correcting the previously-instructed saturation adjustment amount.In this way, the determination in step 110 is negative and thedetermination in step 112 is affirmative, and the processings of steps116 through 128 are repeated on the basis of the new saturationadjustment amount after correction.

Further, in the verification of the output image, for example, if it isjudged that the saturation adjustment amount for the overall image isappropriate but that there are portions where the image quality hasdeteriorated because the change (increase) in saturation is excessive,the operator operates the key correction input section 48 in order tosuppress the saturation change of these portions. The operatordesignates the color region, to which these portions belong, as a colorregion which is the object of saturation change suppression, anddesignates the degree of suppression of the saturation change for thedesignated color region.

For example, it is easy for an unnatural finish to arise if thesaturation of portions corresponding to the green of trees or grass inthe image is high. As a result, in a case in which it is judged that thefinish of such portions in the image is unnatural, the operatordesignates the color region corresponding to green color (the colorregion centered around hue angle H*≈135°) as a color region which is anobject of saturation change suppression.

In the present embodiment, in order to easily carry out designating of acolor region which is an object of saturation change suppression, thehue angle H*, the saturation C* and the lightness L* in the output imageare each divided into plural ranges (e.g., divided into three levels ofhigh/medium/low, or divided into even finer divisions). In this way, thecolor reproduction range of the output image is divided in advance intoa plurality of portion color regions. Due to the operator operating thekey correction input section 48 and selecting, from the plurality ofportion color regions, the color region at which the change insaturation is to be suppressed, the color region which is the object ofsaturation change suppression can be designated.

Note that the designation of the color region which is the object ofsaturation change suppression is not limited to the above-describedmethod. For example, the designation may be carried out by the operatordesignating parameters such as the hue angle, the normalized saturation,the normalized lightness or the like, which prescribe the center or theouter edge of the color region which is the object of saturation changesuppression. (For example, the operator may designate the color regionwhich is the object of saturation change suppression as “color regioncentered around hue angle H*≈135°” or the like.)

With regard to the designation of the degree of suppression of change insaturation as well, in the present embodiment, the degree of suppressionmay be divided into plural levels (e.g., high/medium/low), and theoperator may operate the key correction input section 48 so as to selecta level corresponding to the desired degree of suppression from theplural levels. The degree of suppression of the saturation change may bedesignated in this way.

When the operator inputs the aforementioned information, the answer tothe determination in step 124 is affirmative, and the routine moves onto step 126. In step 126, the saturation adjustment data currently setin the 3D-LUT 44 for saturation adjustment is read out, and the read-outsaturation adjustment data is corrected so as to become a conversioncharacteristic which suppresses the saturation change, in the outputimage, of the designated color region in accordance with the designateddegree of suppression. Thereafter, the routine moves on to step 128.

The correction of the saturation adjustment data can be realized by, forexample, determining saturation adjustment data D” in accordance withthe following formula on the basis of the saturation adjustment data Dbefore correction which is currently set in the 3D-LUT 44 for saturationadjustment and the data D′ (the data for setting in the 3D-LUT) which isset such that the saturation of all of the color regions does notchange.D″=K·D′+(1−K)D

As shown as an example in FIG. 6, the factor K in the above formula is afactor which is determined for a change in the hue angle H* or thesaturation C* or the lightness L* such that the value of K is zero atregions other than a vicinity of the color region designated by theoperator, and the value of K is greater than zero in a vicinity of thedesignated color region. In the example of FIG. 6, plural types offactors K₁, K₂, K₃, whose values (peak values) in the designated colorregion are respectively different, are prepared, and K₁ through K₃ areselectively used in accordance with the degree of suppression ofsaturation change designated by the operator. In this way, thesaturation adjustment data D set at the 3D-LUT 44 for saturationadjustment can be corrected to saturation adjustment data D” of aconversion characteristic which suppresses, in accordance with thedesignated degree of suppression, a change in saturation in the outputimage of the designated color region.

Above-described step 126 corresponds to the generating section recitedin the twelfth aspect. Due to the above-described processes and due tothe processings of steps 128, 106 and 108, an output image, in which thechange in saturation is suppressed at a suppression rate designated bythe operator, for the color region designated by the operator as well,is displayed on the CRT 20.

When the operator judges that the image quality of the output imagedisplayed on the CRT 20 is appropriate and inputs, via the keycorrection input section 48 and as information expressing the results ofverification, information meaning that the image quality is satisfactory(“verification OK”), the answer to the determination in step 110 isaffirmative. The routine moves on to step 130 where informationexpressing the processing conditions which have been decided upon (thelatest processing conditions relayed to the first image processingsection 32) is temporarily stored in the storage portion 50 incorrespondence with image identification information (e.g., the framenumber) which identifies the object image (the image which has beenverified by the operator).

In subsequent step 132, a determination is made as to whether saturationadjustment was instructed by the operator at the time of imageverification. If the answer to this determination is negative, set-upprocessing is completed without any processings being carried out.However, in a case in which saturation adjustment was instructed by theoperator at the time of image verification, the answer to thedetermination in step 132 is affirmative, and the routine moves on tostep 134. In step 134, on the basis of the output form designatinginformation which is attached to the low resolution image data stored inthe prescan memory 28, the output form at the time of outputting theimage by using the high resolution image data expressing the same imageas that low resolution image data is determined, and it is judgedwhether or not the output form is “print output”.

If the output form at the time of outputting the image by using highresolution image data is “print output”, the color reproduction regionof the output image (in this case, the output image recorded onphotographic printing paper) is different than the color reproductionregion of the output image displayed on the CRT 20 at the time of imageverification. Thus, if saturation adjustment is carried out on the highresolution image data by using saturation adjustment data which is thesame as at the time of image verification, there is the possibility thatthe output image displayed on the CRT 20 at the time of imageverification will not be reproduced on photographic printing paper, andthat oversaturation and other problems with image quality will arise inthe output image recorded on the photographic printing paper.

Thus, in a case in which the determination in step 134 is affirmative,the routine moves on to step 136. In the same way as inpreviously-described steps 116 through 126, the saturation adjustmentamount which was ultimately decided upon at the time of imageverification is sensed. Among the saturation adjustment data for “printoutput” stored in the storage portion 50, the saturation adjustmentdata, whose corresponding saturation adjustment amount AC matches or isnear to the saturation adjustment amount which has been sensed, is readout from the storage portion 50. If needed, interpolation computation iscarried out so as to obtain saturation adjustment data whosecorresponding saturation adjustment amount ΔC matches the sensedsaturation adjustment amount.

Further, in a case in which a color region, at which a change insaturation should be suppressed, is designated by the operator at thetime of image verification, the saturation adjustment data is correctedsuch that the change in saturation in the output image for thedesignated color region is suppressed at the degree of suppressiondesignated by the operator. In this way, it is possible to obtainsaturation adjustment data of a conversion characteristic which canconvert high resolution image data such that the output image recordedon the photographic printing paper is of the same image quality as theoutput image displayed on the CRT 20 at the time of image verification.When the processing of step 136 is carried out, the routine moves on tostep 138.

On the other hand, in a case in which the output form at the time ofoutputting the image by using the high resolution image data is “monitordisplay/CD-R writing”, the color reproduction range of the output imageis the same as that at the time of image verification. Saturationadjustment can be carried out on the high resolution image data by usingthe same saturation adjustment data as at the time of imageverification. Thus, the routine moves on to step 138 without anyprocessings being carried out. Note that above-described steps 134, 136correspond to the converting section of the ninth and eleventh aspectsand the generating section of the twelfth aspect, respectively.

In step 138, the saturation adjustment data for the high resolutionimage data which was decided upon by the above-described processings istemporarily stored in the storage portion 50 in correspondence with theprocessing condition information and the image identificationinformation temporarily stored in the storage portion 50 in step 130.Further, in the next step 140, a determination is made as to whether thesaturation adjustment data stored in step 138 is saturation adjustmentdata which has been corrected in accordance with a designation from theoperator of a color region which is an object of saturation changesuppression.

If the answer to the determination is negative, the set-up processing iscompleted. However, if the answer to the determination in step 140 isaffirmative, the saturation adjustment data temporarily stored in thestorage portion 50 in step 138 is registered in a saturation adjustmentdata registration region provided in the storage region of the storageportion 50 separately from the region for the aforementioned temporarystorage. In this way, the saturation adjustment data temporarily storedin the storage portion 50 for saturation adjustment of a specific imagecan be used as well for saturation adjustment of another image.

After set-up processing has been completed, when the high resolutionimage data of the image which is to be outputted in the designatedpredetermined output form is outputted from the image datapre-processing section 26 and stored in the fine scan memory 30, theset-up computation section 34, on the basis of the image identificationinformation of the image expressed by the high resolution image datastored in the fine scan memory 30, reads out from the storage portion 50the processing condition information corresponding to the highresolution image data, outputs the read processing condition informationto the second image processing section 36, and gives instructions thatimage processing is to be carried out.

Further, when the set-up computation section 34 reads out the processingcondition information from the storage portion 50, in a case in whichthe saturation adjustment data is stored in correspondence with theimage identification information and the processing conditioninformation, the saturation adjustment data also is read out from thestorage portion 50. The read-out saturation adjustment data is set inthe 3D-LUT 44 for saturation adjustment, and the selector 42 is switchedsuch that the image data inputted to the selector 42 is inputted to the3D-LUT 44 for saturation adjustment. In a case in which no correspondingsaturation adjustment data is stored in the storage portion 50, theselector 42 is switched such that the image data inputted to theselector 42 bypasses the 3D-LUT 44 for saturation adjustment and isinputted to the selector 46.

Further, the set-up computation section 34 senses the output form of theimage, reads out from the storage portion 50 the density conversion datacorresponding to the sensed output form, sets the density conversiondata in the LUT 40 for density conversion, and switches the selector 46such that the image data inputted to the selector 46 is outputted to anoutput device corresponding to the sensed output form (the laser printer22 or the CD-R writing device 24).

In this way, at the second image processing section 36, the highresolution image data is read out from the fine scan memory 30, andvarious types of image processings are carried out in accordance withthe processing conditions expressed by the processing conditioninformation inputted from the set-up computation section 34. Thereafter,the high resolution image data is outputted to the color reproductionconversion section 38.

The high resolution image data which has been inputted to the colorreproduction conversion section 38 from the second image processingsection 36 is inputted to the LUT 40 for density conversion. On thebasis of the density conversion data set in the LUT 40 for densityconversion by the set-up computation section 34, density conversion iscarried out. In a case in which saturation adjustment data is set in the3D-LUT 44 for saturation adjustment by the set-up computation section34, the high resolution image data for which density conversion has beencarried out is inputted to the 3D-LUT 44 for saturation adjustment, andsaturation adjustment processing is carried out on the basis of thesaturation adjustment data.

Then, the image data, which has been subjected to color reproductionconversion processing by the color reproduction conversion section 38,is outputted, via the selector 46, to an output device corresponding toa predetermined output form, and is recorded as an image ontophotographic printing paper by the laser printer 22 or is written onto aCD-R by the CD-R writing device 24.

In this way, for the image for which saturation adjustment is instructedat the time of image verification, saturation conversion processing iscarried out by the 3D-LUT 44 for saturation adjustment on the basis ofthe saturation adjustment data set by the set-up computation section 34.(If the output form is “monitor display/CD-R writing”, processing iscarried out on the basis of the same saturation adjustment data as thesaturation adjustment data used at the time of image verification. Ifthe output form is “print output”, processing is carried out on thebasis of saturation adjustment data whose saturation adjustment amountand color region which is the object of saturation change suppressionare the same as those of the saturation adjustment data used at the timeof image verification.)

Accordingly, for an output image outputted by using high resolutionimage data (an image recorded on a photographic printing paper or animage displayed on a CRT by using image data recorded on a CD-R), theoverall saturation is changed in accordance with instructions from theoperator, a change in saturation of portions corresponding to the skinof persons is suppressed, and coloring of neutral color portions in theimage, oversaturation of high saturation portions in the image, and agreat change in saturation at the highlight portions and shadow portionscan be prevented. Further, there is no unnatural finish due to portionsarising in which the saturation adjustment amount in the output imagesuddenly changes.

In the above description, saturation adjustment data are set and storedseparately for each of the image output forms of “monitor display/CD-Rwriting” and “print output”. However, the present invention is notlimited to the same. For example, it is possible to set and store onlythe saturation adjustment data corresponding to a specific output form(e.g., “monitor display/CD-R writing”), and to set and store conversiondata for converting the saturation adjustment data corresponding to thespecific output form into saturation adjustment data corresponding toanother output form. In a case in which an image is to be outputted inan output form (e.g., “print output”) other than the specific outputform, the stored saturation adjustment data is converted by theconversion data, such that saturation adjustment data corresponding tothe output form of the image is acquired.

Next, a second embodiment of the present invention will be describedwith reference to FIGS. 7 through 11. In FIG. 7, portions which are thesame as those of the image processing system 10 relating to the firstembodiment of the present invention are denoted by the same referencenumerals, and description thereof is omitted.

In an image processing system 11 of FIG. 7, the color reproductionconversion section 38 is formed by a look-up table (LUT) 60 forgradation conversion for converting the gradation of inputted imagedata, a three-dimensional look-up table (3D-LUT) 62 for color correctionfor correcting a change in image quality accompanying a change ingradation at the LUT 60 for gradation conversion, and a selector 64being connected in that order, such that the image expressed by theinputted image data is appropriately reproduced in the output image (theimage which is made visible on a photographic printing paper in theoutput form of recording images onto a photographic printing paper, oran image displayed on the CRT 20 by using recorded image data in theoutput form of recording image data on a CD-R). The CRT 20, the laserprinter 22 and the CD-R writing device 24 are connected to the outputends of the selector 64.

The LUT 60 for gradation conversion corresponds to the convertingsection of the present invention. The 3D-LUT 62 for color correction andthe set-up computation section 34, which sets the color correction data(to be described in detail later) in the 3D-LUT 62 for color correction,correspond to the control section of the present invention.

Next, operation of the present embodiment will be described withreference to the flowchart in FIG. 8 which shows the set-up processingexecuted at the CPU of the set-up computation section 34. This set-upprocessing is executed by (the CPU of) the set-up computation section 34each time the low resolution image data of a single image is stored inthe prescan memory 28.

In step 200, the low resolution image data stored in the prescan memory28 is fetched, and image data analysis including processings suchextraction of the main portions in the image (e.g., the regionscorresponding to the faces of persons (face regions)), computation ofvarious types of image characteristic amounts, and the like, is carriedout. In step 202, on the basis of the results of analysis of the imagedata in step 200, the optimal processing conditions for the imageprocessing to be carried out at the second image processing section 36on the high resolution image data are computed, and the first imageprocessing section 32 is informed of these computed processingconditions.

In the following step 204, gradation conversion data for carrying outgradation conversion is set in the LUT 60 for gradation conversion, andgradation conversion condition setting processing, which sets, in the3D-LUT 62 for color correction, the color correction data for carryingout color correction, is carried out. This gradation conversioncondition setting processing will be described with reference to theflowchart of FIGS. 9A and 9B.

In the present embodiment, at least gradation conversion data, whichexpresses standard gradation conversion conditions, is stored in advancein the storage portion 50 (which is formed by an HDD) of the set-upcomputation section 34 as gradation conversion data for setting in theLUT 60 for gradation conversion. When the gradation of the image data isto be converted, the saturation and the hue of the image expressed bythe image data are converted. Thus, in the present embodiment, whenimage output is carried out by using, as the color correction data forsetting in the 3D-LUT 62 for color correction, at least image data whichconverts the gradation under standard gradation conditions, colorcorrection data, which expresses color correction conditions (a colorconversion characteristic) determined such that the saturation and thehue in the output image are reproduced as an appropriate image, isstored in the storage portion 50 in correspondence with the gradationconversion data expressing the standard gradation conversion conditions.Note that the storage portion 50 corresponds to the first storingsection and the second storing section of the present invention.

For example, the gradation of the image data expressing a known Macbethchart may be converted in accordance with standard gradation conversionconditions, and by using the image data which has been subjected togradation conversion, the image (Macbeth chart) can be exposed andrecorded onto a photographic printing paper by the laser printer 22, andthe saturation and hue can be evaluated for each patch of the Macbethchart formed on the photographing printing paper. The color correctionconditions (color conversion characteristic) expressed by the colorcorrection data can be determined such that the saturation and hue ofeach patch are appropriate. A Macbeth chart is formed to include, ascolors to be imaged (subject colors), a good balance of patches ofvarious colors which appear frequently (e.g., a plurality of graypatches having respectively different lightnesses, or R, G, B, C, M, Ypatches, or patches of colors such as DarkSkin, LightSkin, BlueSky,Foliage, and the like). The image quality of an image can beappropriately evaluated by using a small number of patches.

The following three output forms are prepared as the image output formsin the present embodiment: displaying the image onto the CRT 20 (monitordisplay), recording the image onto a photographic printing paper by thelaser printer 22 (printer output), and writing the image data onto aCD-R by the CD-R writing device 24 (CD-R writing). However, among these,monitor display is for advance verification of the image quality of animage to be outputted by printing, and a monitor display image requiresthe same level of image quality as a print output image.

Because the image data written onto a CD-R is usually used in display ona CRT monitor, when displaying the image data on the CRT monitor, it ispreferable to display the image data on the CRT monitor at a preferableimage quality without subjecting the image data to any particularpost-processings. As a result, in the present embodiment, colorcorrection data for monitor display and CD-R writing, and colorcorrection data for print output are determined separately as colorcorrection data corresponding to the standard gradation conversionconditions. At the time of monitor display or CD-R writing, color spaceconversion is included in order to make the image quality of the outputimage the same level as that of print output. Then, at the time ofsetting the color correction data into the 3D-LUT 62 for colorcorrection, the color correction data corresponding to the output formis set in the 3D-LUT 62 for color correction.

Further, in order to reduce the data amount of the conversion data to bestored in the 3D-LUT, usually, only the conversion data corresponding tothe peaks (grid points) of respective grid portions, when the data spaceof the data which is to be converted is divided into a large number ofgrid portions, is stored. When data corresponding to an area betweengrid points is inputted, the corresponding conversion data is determinedby interpolation computation from the conversion data of the surroundinggrid points and is outputted. As a result, in the present embodiment,only the conversion data corresponding to the grid points is set ascolor correction data.

In step 250 of the gradation conversion condition setting processing, bydisplaying a predetermined message on the CRT 20 or the like, theoperator is asked whether or not gradation conversion is to be carriedout by using standard gradation conversion conditions. On the basis ofinformation which the operator inputs via the key correction inputsection 48 in response to this query, a determination is made as towhether gradation conversion is to be carried out by using the standardgradation conversion conditions. First, due to the standard gradationconversion conditions being selected by the operator, the answer to thedetermination in step 250 is affirmative, and the routine moves on tostep 252. In step 252, the gradation conversion data expressing thestandard gradation conversion conditions is fetched from the storageportion 50, and the fetched gradation conversion data are set in the LUT60 for gradation conversion.

In next step 254, the color correction data, which is stored iscorrespondence with the gradation conversion data expressing thestandard gradation conversion conditions, is read from the storageportion 50, and is set in the 3D-LUT 62 for color correction. In thisway, gradation conversion can be carried out under the standardgradation conversion conditions on the image data inputted to the colorreproduction conversion section 38, without there being a change inimage quality such as a change in saturation or hue or the like. Then,the selector 66 is switched such that the image data inputted to theselector 66 from the 3D-LUT 62 for color correction is outputted to theCRT 20, and the routine moves on to step 206 of the set-up processing(FIG. 8).

In step 206, the low resolution image data stored in the prescan memory28 is subjected to various types of image processings by the first imageprocessing section 32, and is subjected to color reproduction conversionprocessing by the color reproduction conversion section 38 (gradationconversion processing by the LUT 60 for gradation conversion and colorcorrection processing by the 3D-LUT 62 for color correction).

In this way, the first image processing section 32 fetches the lowresolution image data from the prescan memory 28. On the basis of theprocessing conditions notified by the processing of step 202, the firstimage processing section 32 subjects the low resolution image data toimage processings, which are equivalent to image processings carried outby the second image processing section 36 on the high resolution imagedata, so as to generate simulation image data. The simulation image datagenerated by the first image processing section 32 is subjected to colorreproduction conversion processings by the LUT 60 for gradationconversion and the 3D-LUT 62 for color correction of the colorreproduction conversion section 38.

In step 208, the image data which has been subjected to colorreproduction conversion processing by the color reproduction conversionsection 38 is outputted to the CRT 20. An image expressed by the imagedata is thereby displayed on the CRT 20 as an output image. A messagerequesting that the operator verify the output image displayed on theCRT 20 is also displayed on the CRT 20, so that the operator is made toverify the finish and the like of the respective portions of the outputimage displayed on the CRT 20.

When the output image is displayed on the CRT 20 and verification of theoutput image is requested, the operator visually confirms the outputimage displayed on the CRT 20, and verifies whether or not the imagequality of the output image is appropriate, i.e., whether the processingconditions computed at the set-up computation section 34 areappropriate, and whether the gradation expression of the output image isappropriate. The operator inputs information expressing the results ofverification via the key correction input section 48.

When the operator inputs information expressing the results ofverification via the key correction input section 48, the routine moveson to step 210 where it is judged whether the information expressing theresults of verification which the operator inputted via the keycorrection input section 48 is information meaning that the image hasbeen verified to be satisfactory (“verification OK”). In a case in whichinformation meaning “verification OK” has been inputted, the answer tothe above determination is affirmative, and the routine moves on to step216. However, in a case in which information instructing correction ofthe image processing conditions or information instructing correction ofthe gradation conversion conditions is inputted as the informationexpressing the results of verification, it is judged that the results ofverification by the operator are that the image is unsatisfactory(“verification NG (no good)”), and the routine moves on to step 212.

In step 212, it is judged whether the information expressing theinputted results of verification is information instructing correctionof the gradation conversion conditions. In a case in which informationinstructing correction of the image processing conditions has beeninputted, the determination in step 212 is negative, and the routinemoves on to step 214. In step 214, the image processing conditionscomputed in previous step 202 are corrected in accordance with theinputted instructions, and the first image processing section 32 isinformed of the corrected processing conditions. Thereafter, the routinereturns to step 206.

In this way, at the first image processing section 32, processing forregenerating the simulation image data is carried out in accordance withthe corrected processing conditions, and the regenerated simulationimage data is subjected to color reproduction conversion processing atthe color reproduction conversion section 38, and then outputted to theCRT 20. In this way, an output image is displayed on the CRT 20 on thebasis of the processing conditions which have been corrected inaccordance with the inputted correction instructions. Due to theoperator visually confirming the output image displayed on the CRT 20this time, the operator can easily judge whether or not the contents ofthe inputted correction instructions are appropriate.

On the other hand, in a case in which it is determined that thegradation expression of the output image displayed on the CRT 20 isinappropriate, the operator inputs, via the key correction input section48, information instructing use of gradation conversion conditions otherthan the standard gradation conversion conditions. In this case, thedetermination in step 212 is affirmative, and the routine returns tostep 204, and gradation conversion condition setting processing (FIGS.9A and 9B) is again carried out.

In the gradation conversion condition setting processing, due toinformation instructing the use of gradation conversion conditions otherthan the standard gradation conversion conditions being inputted, thedetermination in step 250 is negative, and the routine moves on to step256. In step 256, by displaying a predetermined message on the CRT 20 orthe like, the operator is asked whether gradation conversion conditionsobtained by correcting the gradation conversion conditions which arecurrently set should be used in gradation conversion. The processingdiverges on the basis of the information which the operator has inputtedthrough the key correction input section 48 in response to this query.In a case in which correction of the gradation conversion conditionswhich are currently set is instructed, the routine moves from step 256to step 258 where a gradation conversion condition correction screen,which allows the operator to instruct correction of the gradationconversion conditions, is displayed on the CRT 20.

As an example, as shown in FIG. 10, the gradation conversion conditioncorrection screen is provided with the buttons “hard gradationenhancement”, “no correction”, “soft gradation enhancement” forrespective density regions obtained by dividing the entire density rangeof the image, from highlight to shadow, into three density regions(highlight region, intermediate gradation region, and shadow region). Bythe operator operating a mouse or the like of the key correction inputsection 48 and clicking on a desired button, it is possible toarbitrarily instruct, for each density region, correction of the slope(γ) of the gradation conversion conditions. (The entire density regionmay be divided into more regions or fewer regions than theaforementioned three regions. Further, a single slope may be set for theentire density region.) In next step 260, it is judged whether input ofinformation for correcting the gradation conversion conditions has beencompleted, and the routine waits until input is completed.

In this way, by the operator operating the key correction input section48, the gradation conversion conditions which are currently set can bearbitrarily corrected such that optimal gradation conversion conditionscorresponding to the type of the photographed subject existing in theimage or the application of the image (i.e., desired gradationconversion conditions) can be obtained. When the operator completesinput of information for correcting the gradation conversion conditions,the answer to the determination in step 260 is affirmative. The routinemoves on to step 262 where the conversion data expressing the gradationconversion conditions which are the object of correction (the gradationconversion conditions which are currently set) are corrected inaccordance with the instructions for correction inputted by theoperator.

For example, gradation conversion conditions such as shown in FIG. 11Aare set as the gradation conversion conditions. In a case in which, forexample, as shown in FIG. 11B, “hard gradation enhancement” is selectedfor the highlight region, “soft gradation enhancement” is set for theintermediate gradation region, and “no correction” is selected for theshadow region, the correction of the gradation conversion conditions canbe carried out by superposing (cascading) the gradation conversionconditions currently set and the gradation conversion conditionsstipulated by the inputted correction instruction. In this way,conversion data expressing the gradation conversion conditions shown bythe solid line in FIG. 11C can be obtained.

Then, when the gradation conversion data, which express the gradationconversion conditions desired by the operator, are obtained as describedabove, the obtained gradation conversion data is set in the LUT 60 forgradation conversion. In this way, gradation conversion is carried out,by the LUT 60 for gradation conversion and under the gradationconversion conditions desired by the operator, on the image datainputted to the color reproduction conversion section 38.

In steps from step 264 on, color correction conditions, which correctchanges in saturation or hue or the like at the time that gradationconversion is carried out by using the corrected gradation conversionconditions, are computed as color correction conditions corresponding tothe corrected gradation conversion conditions. Namely, in step 264, RGBvalues (R0n, G0n, B0n) at the time of converting back, under thecorrected gradation conversion conditions, the input values R1′n, G1′n,B1′n (the input values at the respective grid points are fixedlydetermined) at specific grid points (wherein n is the grid point) of the3D-LUT 62 for color correction, are computed.

In subsequent step 266, the RGB values R1n, G1n, B1n at the time ofconverting the RGB values R0n, G0n, B0n under the standard gradationconversion conditions are computed. In step 268, RGB values (R2n, G2n,B2n) at the time of correcting (converting) the RGB values R1n, G1n, B1nat color correction conditions corresponding to the standard gradationconversion conditions, are computed. In step 270, the color correctiondata Rout, Gout, Bout (=R2′n, G2′n, B2′n) expressing the colorconversion conditions at grid point n, among the color correctionconditions corresponding to the corrected gradation conversionconditions, are computed in accordance with the following formulas.$\begin{matrix}{{Rout} = {{R2}^{\prime}n}} \\{= {{R2n} - {\left( {{R2n} + {G2n} + {B2n}} \right)/3} + {\left( {{{R2}^{\prime}n} + {{G2}^{\prime}n} + {{B2}^{\prime}n}} \right)/3}}} \\{{Gout} = {{G2}^{\prime}n}} \\{= {{G2n} - {\left( {{R2n} + {G2n} + {B2n}} \right)/3} + {\left( {{{R2}^{\prime}n} + {{G2}^{\prime}n} + {{B2}^{\prime}n}} \right)/3}}} \\{{Bout} = {{B2}^{\prime}n}} \\{= {{B2n} - {\left( {{R2n} + {G2n} + {B2n}} \right)/3} + {\left( {{{R2}^{\prime}n} + {{G2}^{\prime}n} + {{B2}^{\prime}n}} \right)/3}}}\end{matrix}$

In the next step 272, a determination is made as to whether thecomputations of steps 264 through 270 have been carried out for all ofthe grid points of the 3D-LUT 62 for color correction. When thedetermination is negative, the routine returns to step 264, and steps264 through 272 are repeated.

The RGB values R2n, G2n, B2n determined in step 268 are RGB values in acase in which the RGB values (image data) R0n, G0n, B0n are converted inaccordance with the standard gradation conversion conditions, and areagain corrected (converted) in accordance with color correctionconditions corresponding to the standard gradation conversionconditions. On the other hand, the RGB values R2′n, G2′n, B2′n whichsatisfy the above formulas and the RGB values R2′n, G2′n, B2′n have thesame ratio of the difference, for each of RGB, to the RGB value (whichis (R2′n+G2′n+B2′n)/3) of a pixel whose hue is gray and whose lightnessis substantially the same as that of a pixel whose RGB values are R2′n,G2′n, B2′n, with respect to those of the RGB values R2n, G2n, B2n. Thus,pixels whose RGB values=R2′n, G2′n, B2′n are visually recognized aspixels having the same saturation and hue as pixels whose RGBvalues=R2n, G2n, B2n.

As a result, as described above, the color correction data of therespective grid points of the 3D-LUT 62 for color correction are setsuch that the RGB values R1′n, G1′n, B1′n at the time of converting theRGB values (image data) R0n, G0n, B0n in accordance with the correctedgradation conversion conditions are converted to the RGB values R2′n,G2′n, B2′n (=Rout, Gout, Bout) by the color correction. In this way,color correction conditions (color correction data), which can correctthe changes in the saturation, hue or the like at the time thatgradation conversion is carried out by using corrected gradationconversion conditions, can be obtained.

When the color correction data is set for all of the grid points, theanswer to the determination in step 272 is affirmative, and the routinemoves on to step 274 where the obtained color correction data is set inthe 3D-LUT 60 for color correction. In this way, gradation conversioncan be carried out on the image data inputted to the color reproductionconversion section 38 under the gradation conversion conditions desiredby the operator, without changes in image quality, such as changes inthe saturation or hue or the like, arising.

As described above, there are two types of color correction datacorresponding to standard gradation conversion conditions: colorcorrection data for monitor display and CD-R writing, and colorcorrection data for print output. Thus, the processings ofabove-described steps 264 through 272 are carried out respectively byusing the two types of color correction data. In step 274, among the twotypes of color correction data corresponding to the corrected gradationconversion conditions, the color correction data for monitor display andCD-R writing are set in the 3D-LUT 60 for color correction.

In next step 276, by displaying a predetermined message on the CRT 20 orthe like, the operator is asked whether or not the corrected gradationconversion conditions and the color correction conditions correspondingto these gradation conversion conditions are to be registered in thestorage portion 50. On the basis of information which the operatorinputs via the key correction input section 46 in response to thisquery, a determination is made as to whether the corrected gradationconversion conditions and the corresponding color correction conditionsare to be registered in the storage portion 50.

When the answer to the determination is negative, the conversioncondition setting processing ends without any processings being carriedout. When the answer to the determination is affirmative, the routinemoves on to step 278. In step 278, the gradation conversion dataexpressing the corrected gradation conversion conditions and the colorcorrection data expressing the corresponding color correction conditionsare registered in the storage portion 50 in correspondence with aregistration name which the operator inputs via the key correction inputsection 48. Thereafter, the conversion condition setting processingends, and the routine moves on to step 206 of the set-up processing (seeFIG. 8). In this way, the gradation conversion conditions which havebeen newly set this time and the corresponding color correctionconditions are registered in the storage portion 50, and can thereby beused in gradation conversion and color correction of the image data ofother images as will be described later.

Further, in a case in which instructions are given that gradationconversion conditions which have already been registered in the storageportion 50 are to be used as the gradation conversion conditions otherthan the standard gradation conversion conditions, the determinations instep 250 and step 256 are both negative, and the routine moves on tostep 280. In step 280, the registration names of all of the gradationconversion conditions which have already been registered in the storageportion 50 are displayed in a list on the CRT 20, and a predeterminedmessage is displayed on the CRT 20 asking the operator to select one ofthe gradation conversion conditions from among the gradation conversionconditions whose registration names are displayed. In the next step 282,a determination is made as to whether any of the gradation conversionconditions have been selected, and the routine stands by until theanswer to this determination is affirmative.

When the operator, in accordance with the message displayed on the CRT,selects, via the key correction input section 48, a registration namecorresponding to the desired gradation conversion conditions from amongthe registration names which are displayed in a list on the CRT 20, thedetermination in step 282 is affirmative, and the routine moves on tostep 284. In step 284, the gradation conversion data of the gradationconversion conditions which correspond to the selected registration nameare fetched from the storage portion 50, and the fetched gradationconversion data is set in the LUT 50 for gradation conversion. In step286, the color correction data of the color correction conditionscorresponding to the gradation conversion conditions are fetched fromthe storage portion 50, and are set in the 3D-LUT 62 for colorcorrection. Thereafter, the conversion condition setting processingends, and the routine moves on to step 206 of the set-up processing (seeFIG. 8).

In this way, gradation conversion can be carried out on the image datainputted to the color reproduction conversion section 38 under thegradation conversion conditions desired by the operator, without changesin image quality, such as changes in the saturation or hue or the like,arising.

Further, in step 206 of the set-up processing, the first imageprocessing section 32 regenerates simulation image data. Further, theregenerated simulation image data is subjected to color reproductionconversion processing at the color reproduction conversion section 38(gradation conversion is carried out in accordance with gradationconversion conditions other than the standard gradation conversionconditions, and color correction is carried out in accordance with thecolor correction conditions which are set such that changes in imagequality, such as changes in saturation or hue or the like, do notarise). The data is then outputted to the CRT 20, and the output imageis thereby displayed again on the CRT 20. By operator visuallyconfirming the gradation expression of the output image which isdisplayed on the CRT 20, the operator can easily judge whether or notthe current gradation conversion conditions are appropriate.

When the operator judges whether the image quality of the output imagedisplayed on the CRT 20 is appropriate, and inputs, via the keycorrection input section 48 and as information expressing the results ofverification, information meaning “verification OK”, the answer to thedetermination in step 210 is affirmative. The routine moves on to step216 where the decided-upon processing conditions (the latest processingconditions relayed to the first image processing section 32), thegradation conversion conditions (gradation conversion data) set in theLUT 60 for gradation conversion, and, among the two types of colorcorrection data corresponding to these gradation conversion conditions,the color correction data corresponding to the output form of the image(the color correction data for print output in the case in which theoutput form is print output, and the color correction data for monitordisplay and CD-R writing in a case in which the output form is monitordisplay or CD-R writing) are temporarily stored in the storage portion50 in correspondence with image identification information (e.g., theframe number) which identifies the object image (the image which isverified by the operator). The set-up processing then ends.

After set-up processing has been completed, when the high resolutionimage data of the image which is to be outputted in the designated,predetermined output form is outputted from the image datapre-processing section 26 and stored in the fine scan memory 30, on thebasis of the image identification information of the image expressed bythe high resolution image data stored in the fine scan memory 30, theset-up processing section 34 reads from the storage portion 50 theprocessing condition information corresponding to the high resolutionimage data, and outputs the read processing condition information to thesecond image processing section 36, and gives instructions that imageprocessing is to be carried out.

Further, when the set-up computation section 34 reads the processingcondition information from the storage portion 50, the set-upcomputation section 34 also reads out from the storage portion 50 thegradation conversion data and the color correction data (colorcorrection data corresponding to the output form of the image) which arestored in correspondence with the image identification information andthe processing condition information. The set-up processing section 34sets the read-out gradation conversion data in the LUT 60 for gradationconversion, and sets the read-out color correction data in the 3D-LUT 62for color correction, and switches the selector 66 such that the imagedata inputted to the selector 66 is outputted to the output device (thelaser printer 22 or the CD-R writing device 24) corresponding to theoutput form of the image.

In this way, at the second image processing section 36, the highresolution image data is read-out from the fine scan memory 30, andafter being subjected to various types of image processings inaccordance with the processing conditions expressed by the processingcondition information inputted from the set-up computation section 34,is outputted to the color reproduction conversion section 38.

The high resolution image data inputted to the color reproductionconversion section 38 from the second image processing section 36 issubjected to gradation conversion by the LUT 60 for gradation conversionin accordance with the gradation conversion data set in the LUT 60 forgradation conversion, and is subjected to color correction by the 3D-LUT62 for color correction in accordance with the color correction data setin the 3D-LUT 62 for color correction. Thereafter, the data is outputtedto an output device corresponding to the predetermined output form, andis either recorded as an image onto photographic printing paper by thelaser printer 22 or written onto a CD-R by the CD-R writing device 24.

In this way, for output images which are outputted by using highresolution image data (images recorded onto photographic printing paperor images displayed on a CRT by using image data recorded on a CD-R),the gradation can be converted in accordance with instructions of theoperator, and changes in image quality, such as changes in saturation orhue or the like, can be prevented from arising.

Note that, in the above description, gradation conversion is carried outby using a one-dimensional LUT. However, the present invention is notlimited to the same. For example, a 3D-LUT may be provided as the LUTfor gradation conversion, and gradation conversion may be carried outindependently for each of the color components (e.g., R, G, B).

Further, in the above description, gradation conversion is carried outby the LUT 60 for gradation conversion, and color correction is carriedout by the 3D-LUT 62 for color correction. However, the presentinvention is not limited to the same. Conversion data, which expresses aconversion characteristic in which are superposed gradation conversionconditions stipulated by gradation conversion data and color correctionconditions stipulated by color correction data, may be set in a single3D-LUT, and gradation conversion and color conversion may be carried outsimultaneously by converting the image data by this single 3D-LUT.

Further, in the above-described example of carrying out gradationconversion and color correction simultaneously by using a single 3D-LUT,conversion data, which carries out gradation conversion in accordancewith a designated color conversion characteristic, may be set for onlypixels, among the inputted image data, whose hues are gray or near gray.In this way, it is possible to realize color conversion by an arbitrarygradation conversion characteristic without changes in saturation or huearising.

Further, the correction of the change in the ratio of the difference ofeach color component with respect to the gray of each pixel in the imagedata is not limited to being carried out by converting the image data byusing a multidimensional look-up table as described above. For example,the above-described correction (reconversion of the image data) can becarried out by substituting values of the respective color components ofthe respective pixels of the image data into a conversion formula whichexpresses a desired conversion characteristic by a function or the like.

As described above, in the inventions of the first through fourteenthaspects, conversion data of a conversion characteristic, which changes,in units of respective pixels and by a predetermined amount, thesaturation, in a visible image, of image data used in outputting avisible image, is stored. When the image data is converted in accordancewith the stored conversion data, the conversion data is of a conversioncharacteristic that suppresses the change in saturation in the visibleimage, for pixels belonging to a predetermined color region. Thus, thereis the excellent effect that the saturation of the image can be adjustedwithout leading to a deterioration in image quality.

In the second aspect of the present invention, in the invention of thefirst aspect, the predetermined color region is a region in which thehue angle in the visible image falls within a predetermined range. Thus,in addition to the above-described effect, there is the effect that achange in saturation of pixels which become a specific hue in thevisible image can be suppressed.

In the third aspect of the present invention, in the invention of thesecond aspect, the predetermined range is a range corresponding to skincolor. Thus, in addition to the above-described effects, there are theeffects that a change in the saturation of portions, in the visibleimage, corresponding to the skin of persons can be suppressed, and adeterioration in image quality at portions which deteriorationaccompanies the change in saturation of the visible image can beeffectively suppressed.

In the fourth aspect of the present invention, in the invention of thefirst aspect, the predetermined color region includes at least one of alow saturation region in which the saturation in the visible image islow and a high saturation region in which the saturation in the visibleimage is high. Thus, in addition to the above-described effect, there isthe effect that, even in a case in which the saturation of the visibleimage is greatly raised or the like, a deterioration in image quality atat least one of the low saturation portion and the high saturationportion in the visible image can be prevented.

In the fifth aspect of the present invention, in the invention of thefirst aspect, the predetermined color region includes at least one of ahigh lightness region in which the lightness in the visible image ishigh and a low lightness region in which the lightness in the visibleimage is low. Thus, in addition to the above-described effect, there isthe effect that, even in a case in which the saturation of the visibleimage is greatly raised or the like, a deterioration in image quality atat least one of the low lightness portion and the high lightness portionin the visible image can be prevented.

In the sixth aspect of the present invention, in the invention of any ofthe first through fifth aspects, the conversion characteristic of theconversion data is set such that, the closer to the predetermined colorregion, the greater the degree of suppression of a change in saturationin the visible image for pixels positioned within the predeterminedregion in a vicinity of the border. Thus, in addition to theabove-described effects, there is the effect that the finish in avicinity of the outer edge of a portion corresponding to thepredetermined color region in the visible image can be prevented frombeing unnatural.

In the eighth aspect of the present invention, in the invention of thefirst aspect, the conversion characteristic of the conversion data isset, on the basis of the color reproduction range in the output form ofthe visible image, such that the change in saturation does not becomesaturated. Thus, in addition to the above-described effect, there is theeffect that a deterioration in image quality such as oversaturation orthe like in the visible image can reliably be prevented.

In the ninth aspect of the present invention, in the invention of thefirst aspect, a plurality of types of conversion data, whose saturationchange amounts are respectively different, are stored, and the imagedata is converted by using the conversion data corresponding to thesaturation change amount instructed via the instructing section. Thus,in addition to the above-described effect, there is the effect that avisible image which has been adjusted to a saturation desired by theoperator can be easily obtained.

In the tenth aspect of the present invention, in the invention of theninth aspect, conversion data corresponding to an instructed saturationchange amount is determined by interpolation, on the basis of conversiondata corresponding to a saturation change amount which approximates asaturation change amount instructed via the instructing section, byusing, as the plural types of conversion data, different conversion datawhose saturation change amounts are respectively greater than or equalto a predetermined value. Thus, in addition to the above-describedeffects, there is the effect that the storage capacity required forstoring the conversion data can be reduced.

In the eleventh aspect of the present invention, in the invention of thefirst aspect, on the basis of respectively different color reproductionranges in plural types of output forms of the visible image, pluraltypes of conversion data, whose conversion characteristics are set suchthat the saturation changes do not become saturated, are respectivelystored, and the image data is converted by using the conversion datacorresponding to the output form which is being used. Thus, in additionto the above-described effect, there is the effect that a visible imagewhose saturation has been changed appropriately can be obtainedregardless of the output form of the visible image.

In the twelfth aspect of the present invention, in the invention of thefirst aspect, when a color region for which a change in saturation is tobe suppressed is designated via the designating section, conversion dataof a conversion characteristic which suppresses a saturation change inthe visible image is generated for the pixels belonging to at least oneof the predetermined color region and the color region designated viathe designating section. Thus, in addition to the above-describedeffect, there is the effect that the saturation of the image can bechanged at a desired conversion characteristic.

In the thirteenth aspect of the present invention, in the invention ofthe first aspect, an image, which is expressed by image data which hasbeen converted by the converting section, is displayed on a displaysection. Thus, in addition to the above-described effect, there is theeffect that the operator can easily confirm whether the saturation hasbeen changed accurately.

Further, as described above, in the present invention, the conversioncharacteristic of the conversion section is controlled such that thegradation of the image data is converted in accordance with a designatedconversion characteristic. Further, the image data which has undergoneconversion by the converting section is reconverted or the conversioncharacteristic of the converting section is controlled such that changesin the ratios of the differences of the respective color components withrespect to the gray of each pixel of the image data, which changesaccompany the gradation of the image data being converted in accordancewith the designated conversion characteristic, are respectivelycorrected. Thus, an excellent effect is achieved in that changes inimage quality, which changes accompany the conversion of the gradation,can be accurately corrected.

1. An image processing device comprising: a converting section forconverting image data; a designating section for designating aconversion characteristic of gradation conversion of the image data; anda control section for controlling a conversion characteristic of theconverting section such that a gradation of the image data is convertedin accordance with a conversion characteristic which is designated viathe designating section, and for one of reconverting image data which isconverted by the converting section and controlling the conversioncharacteristic of the converting section, such that changes in a ratioof a difference, of each of color components, with respect to gray ofeach pixel of the image data, which changes accompany conversion of thegradation of the image data in accordance with the designated conversioncharacteristic, are corrected.
 2. An image processing device accordingto claim 1, wherein the image data is image data obtained byilluminating light onto a photographic film and converting light, whichhas passed through a region at which an image is recorded on thephotographic film, into an electric signal by a photoelectric conversionsensor.
 3. An image processing device according to claim 1, wherein thecontrol section one of reconverts the image data and controls theconversion characteristic of the converting section, in accordance witha conversion characteristic which satisfies the following expressions:R2′−(R2′+G2′+B2′)/3≈R2−(R2+G2+B2)/3,G2′−(R2′+G2′+B2′)/3≈G2−(R2+G2+B2)/3,B2′−(R2′+G2′+B2′)/3≈B2−(R2+G2+B2)/3, where R2′, G2′, B2′are colorcomponent values of respective pixels of image data when image data,whose gradation has been converted in accordance with the designatedconversion characteristic, is converted, and R2, G2, B2 are colorcomponent values of respective pixels of image data when image data,whose gradation has not been converted, is converted.
 4. An imageprocessing device according to claim 1, wherein the control sectionincludes a multidimensional look-up table, and sets, in themultidimensional look-up table, conversion data which is set such thatchanges in a ratio of a difference, of each of color components, withrespect to gray of each pixel of the image data, which changes accompanyconversion of the gradation of the image data by the converting section,are corrected, and reconverts, by the multidimensional look-up table atwhich the conversion data is set, image data which is converted by theconverting section.
 5. An image processing device according to claim 1,wherein the converting section converts the image data by amultidimensional look-up table, and the control section controls theconversion characteristic of the converting section by setting, in themultidimensional look-up table, conversion data of a conversioncharacteristic in which are superposed the conversion characteristicdesignated via the designating section and a conversion characteristicwhich corrects changes in a ratio of a difference, of each of colorcomponents, with respect to gray of each pixel of the image data at atime when gradation of the image data is converted in accordance withthe conversion characteristic designated via the designating section. 6.An image processing device according to claim 1, wherein the convertingsection converts the image data by a multidimensional look-up table, andthe control section controls the conversion characteristic of theconverting section by setting, in the multidimensional look-up table,conversion data of a conversion characteristic which converts, inaccordance with the conversion characteristic designated via thedesignating section, only data corresponding to an achromatic colorportion among image data inputted to the multidimensional look-up table.7. An image processing device according to claim 1, wherein a slope ofthe conversion characteristic is designated via the designating sectionas the conversion characteristic of gradation conversion of the imagedata.
 8. An image processing device according to claim 1, wherein, whena range from highlight through shadow is divided into plural ranges, theconversion characteristic of gradation conversion of the image data isdesignated independently for each of the plural ranges via thedesignating section.
 9. An image processing device according to claim 1,further comprising a first storing section for storing plural types ofconversion characteristics, wherein the conversion characteristic ofgradation conversion of the image data is designated via the designatingsection by a specific conversion characteristic being selected fromamong the plural types of conversion characteristics stored in the firststoring section.
 10. An image processing device according to claim 1,further comprising a second storing section for storing a conversioncharacteristic designated via the designating section, wherein theconversion characteristic of gradation conversion of the image data isdesignated by correction of the conversion characteristic stored in thesecond storing section being designated via the designating section. 11.An image processing method wherein, when a conversion characteristic ofgradation conversion of image data is designated via a designatingsection, a conversion characteristic of conversion of the image data iscontrolled such that a gradation of the image data is converted inaccordance with a conversion characteristic which is designated via adesignating section, and image data which is converted is reconverted orthe conversion characteristic of conversion of the image data iscontrolled, such that changes in a ratio of a difference, of each ofcolor components, with respect to gray of each pixel of the image data,which changes accompany conversion of the gradation of the image data inaccordance with the designated conversion characteristic, are corrected.12. An image processing device according to claim 1, wherein the controlsection reconverts the image data which is converted by the convertingsection or controls the conversion characteristic of the convertingsection, such that the ratio of the difference, of each of colorcomponents, with respect to gray of each pixel of the image data, due tothe conversion of the gradation of the image data in accordance with thedesignated conversion characteristic, and a ratio of a difference, ofeach of color components, with respect to gray of each pixel of theimage data, before the conversion of the gradation of the image data isperformed, are substantially the same.
 13. An image processing methodaccording to claim 11, wherein the image data which is converted isreconverted or the conversion characteristic of conversion of the imagedata is controlled, such that the ratio of the difference, of each ofcolor components, with respect to gray of each pixel of the image data,due to the conversion of the gradation of the image data in accordancewith the designated conversion characteristic, and a ratio of adifference, of each of color components, with respect to gray of eachpixel of the image data, before the conversion of the gradation of theimage data is performed, are substantially the same.